Biochemistry Multiple choice Questions & Answers
Best Biochemistry Objective type Questions and Answers
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1- Which of the following is true concerning a 68 year old male with type 2 diabetes diagnosed with type IV renal tubal acidosis?
1) Aminoaciduria would be expected.
2) Fludrocortisone treatment is effective
3) Increased Glomerular filtration rate is expected.
4) Increased urinary bicarbonate would be expected.
5) Normal renal handling of K+ and H+
Answers-2
H+ secretion, sodium reabsorption and ammonia production diminishes. RTA 4 is in effect hyporeninaemic hypoaldosteronism or failure of aldosterone action and thus helped treated with mineralocorticoids. It is usually seen in chronic renal disease and hence low GFR and particularly. Aminoaciduria and increased urine bicarbonate are features of RTA types 1 and 2.
2- A 16 year old male with a day history of malaise, weakness and vomiting. He was diagnosed with Insulin dependent diabetes mellitus 3 years prviously. Which ONE of the following supports a diagnosis of diabetic ketoacidosis:
1) Abdominal pain at onset
2) A serum bicarbonate of 10 mmol/l
3) A serum glucose 14 mmol/l
4) Decreased appetite in the past few days
5) Shallow respirations
Answers-2
a-An unusual but recognised feature particularly in children. However does not support a diagnosis of DKA. b-Suggests metabolic acidosis. c-'Normoglycaemic
DKA' can occur and a glucose of 14 doesn't rule out the diagnosis but it does not support the diagnosis. d-Usually patients are unwell with infections and anorexia.
e-Respiratory compensation leads to rapid deep (Kussmaul's) breathing. (Dr Mike Mulcahy)
3- Which of the following statements concerning abnormalities of the haemoglobin molecule is true?
1) Alpha thalassaemia is due to a deficiency of beta-chain production
2) HbS is caused by a single base mutation on the beta-chain
3) genes for the alpha and beta chains are located on the same chromosome
4) in thalassaemia persistance of HbF is an adverse prognostic sign
5) oliguneoclitide probes may assist in the diagnosis of haemoglobinopathies
Answers-2
Alpha Thalassaemia is due to abnormalities of the alpha chain. Persistence of HbF has survival advnatages in severely affected subjects. C-alpha 16, beta 11. e-Hb electrophoresis(Dr Shu Ho)
4- Which of the following is a characteristic feature of familial hypercholesterolaemia?
1) Autosomal dominant inheritance
2) elevated chylomicrons
3) hypertriglyceridaemia
4) increased expression of LDL receptors
5) Palmar xanthomas
Answers-1
Familial hypercholesterolaemia is an autosomal dominant condition manifest by increased LDL concentrations (not chylomicrons) due to constitutional abnormalities and reduced numbers of the LDL receptor. Hypertriglyceridaemia is not characteristic and HDL concentrations are usually decreased. Tendon xanthomata are characteristic and the condition is associated with a premature cardiovascular mortality.
5- Which one of the following is a feature of the VIPoma syndrome?
1) Alkalosis
2) Hypoglycaemia
3) Hypokalaemia
4) Increased gastric acid seceretion
5) Provocation of VIP release by somatostatin
Answers-3
a, b,d,e: All opposite to what is expected. VIPOMA -Features vasoactive intestinal polypeptide secreting tumour, mainly pancreas rarely ganglioneuroblatoma
(sympathetic chain or adrenal cortex), secretory diarrhoea ('pancreatic cholera'), weight loss, dehydration, abdominal colic, cutaneous flushing, raised plasma VIP, urea+Calcium, raised plasma pancreatic polypeptide, hypokalaemic acidosis (loss of alkaline secretions), achlorydia, mildly raised glucose, normal functions of VIP. - increased intestinal secretion water and electrolytes -peripheral vasodilation - inhibits gastric acid secretion -potentiates acetylcholine action on salivary glands
6- In which of the following is mental retardation an expected finding?
1) Alkaptonuria
2) Cystinuria
3) Glycogen storage disease
4) Lactose intolerance
5) Maple syrup urine disease
Answers-5
MENTAL RETARDATION. Fragile X syndrome-commonest male cause. Hypoxia at birth, intaventricular haemorrhage, rhesus disease, Congenital infections - toxoplasmosis, CMV, rubella, herpes), hypoglycaemia, meningitis, hypothyroidism (cretinism, tuberous sclerosis, Down's, Tay-Sach's, Cornelia De Lange, Hartnup - biochemical, treatable with diet. -homocystinuria, phenylketonuria -maple syrup urine disease, tryptophanuria -galactosaemia
7- Leukotrienes:
1) Are formed from the cyclooxygenase pathway
2) Are synthesized by fibroblasts
3) Decrease vascular permeability
4) Leukotriene D4 has been identified as SRS-A which causes bronchial wall smooth muscle relaxation
5) Stimulate mucus secretion
Answers-5
Leukotrienes are synthesized by leucocytes.They are mediators of allergic reaction.
They increase vascular permeability and attract neutrophils and eosinophils to inflammatory sites. Leukotrienes are synthesised via the lipoxygenase pathway.
Leukotriene D4 has been identified as SRS-A which causes bronchial wall and intestinal smooth muscle contraction (not dilatation). Leukotrienes also stimulate
mucus production, an important consideration in the pathophysiology of bronchial asthma.
8- Serum biochemistry of a 60 year old man revealed calcium of 1.98 mmol/l and phosphate of 0.55 mmol/l with an alkaline phosphatase of 450 IU/l.Which among the following mosts suits with the above serum biochemistry?
1) Osteoporosis
2) Osteomalacia
3) Pagets Disease
4) Secondary Hyperparathyroidism
5) Renal failure
Answers-2
Osteomalacia is associated with low calcium and phosphate with raised alkaline phosphatase. Serum biochemistry is normal in osteoporosis. Pagets disease is
associated with normal calcium and phosphate with raised alkaline phosphatase.
In renal failure when tertiary hyperparathyroidism sets in there is low calcium with raised phosphate.
9- Low uptake of 123I on the thyroid uptake scan would be an expected finding in:
1) A solitary toxic nodule
2) A multi-nodular toxic goitre
3) Amiodarone induced thyrotoxicosis type 1
4) DeQuervain's thyroiditis
5) Graves' thyrotoxicosis
Answers-4
DeQuervain's thyroiditis is classically associated with low or absent 123I (the 131 radioactive isotope of iodine) uptake. The others will have high or normal uptake.
In particular type 1 amiodarone induced thyrotoxicosis may be distinguished from the thyroiditis of type 2 by the normal or high uptake scan.
10- A 55 year-old female complaining of vague tiredness is found to have a serum corrected calcium concentration of 2.9 mmol/l. Examination was unremarkable. Which of the following results confirms the suspected diagnosis of primary hyperparathyroidism?
1) High normal 1,25-dihydroxyvitamin D concentration
2) High normal 24 hour urinary calcium concentration
3) High normal plasma parathyroid hormone concentration
4) Low normal plasma phosphate concentration
5) Low normal serum 25-hydroxyvitamin D concentration
Answers-3
Bit too easy really. A high or even normal PTH concentration in the presence of hypercalcaemia would support the diagnosis of hyperparathyroidism. A high
urinary Calcium concentration may be expected as would a low plasma phosphate but neither confirm the diagnosis. Elevated 1,25 VitD suggests a diagnosis of
hypervitaminosis D.
11- Gaucher's Disease is associated with the deficiency of :
1) Hexosaminidase A
2) Sphingomyelinase
3) Arylsulphatase-A
4) B- Glucosidase
5) Iduronidase
Answers-4
Hexosaminidase A deficiency is associated Tay-Sachs disease. Sphingomyelinase deficiency is associated with Niemann-Pick disease. Arylsulphatase-A deficiency is associated with metachromic leucodystrophy.Iduronidase deficiency is associated with Hurlers syndrome.
12- Which of the following is activated by Cholera toxin?
1) Adenylate cyclase
2) Guanlyate cyclase
3) Peroxisome proliferator receptor (PPAR) gamma
4) Sodium/potassium ATPase
5) The glucose-sodium transporter
Answers-1
Cholera toxin activates adenylate cyclase with generation of cAMP.
13- Which of the following is true of Gilbert's syndrome?
1) inheritance is autosomal recessive
2) serum conjugated bilirubin levels are elevated
3) serum bilirubin levels are decreased by fasting
4) serum bilirubin levels are decreased by liver enzyme inducers
5) there is bilirubinuria
Answers-4
Gilbert's syndrome is inherited in autosomal dominant fashion and affects 2-5% of the population. UDP glucuronyl transferase levels are reduced leading to an
unconjugated hyperbilirubinaemia. Whilst serum bilirubin levels are elevated the other LFTs are normal. Jaundice deepens after a period of fasting or intercurrent illness but bilirubin levels are reduced by enzyme inducers such as phenobarbitone. As unconjugated bilirubin is tightly bound to albumin it cannot cross the glomerulus and so is not found in the urine. This contrasts with the bilirubin-glucuronide-albumin complex formed in patients with cholestatic jaundice
(and raised conjugated bilirubin levels) where 1% of the complex is dialysable and although most of the bilirubin is reabsorbed in the proximal tubule some bilirubin is detectable in the urine.
14- With respect to lipoprotein transport and metabolism in the body, the following statements are correct EXCEPT:
1) Arterial walls contain cells with LDL receptors.
2) Cholesterol is required for the formation of red blood cell membranes.
3) Chylomicrons are synthesized in the liver.
4) HDL is assembled in the extracellular space.
5) VLDL transformation to LDL occurs in adipose tissue.
Answers-3
Chylomicrons are formed in the gut from exogenous triacylglycerols and cholesterol. They are released into the lymph and thereby enter the blood.They are not formed in the liver.
15- Which ONE of the following is true concerning Antidiuretic hormone(ADH)?
1) Carbamazepine potentiates it's release
2) Ethanol potentiates it's release
3) It circulates in the blood bound to neurohypophysin
4) It is a cyclic octapeptide
5) It is synthesised in the posterior pituitary
Answers-1
ADH is a nonapeptide manufactured in the paraventricular and supra-optic nuclei of the hypothalamus and released from the posterior pituitary. It acts on the
collecting ducts improving water permeability and hence water retention. Carbamazepine as well as other agents such as thiazides and SSRIs may potentiate its release. Ethanol usually inhibits release.
16- A 75 year old man presents with a long history of shortness of breath and ankle oedema. His serum biochemistry shows sodium 122 mmols/l and potassium of 2.9 mmols/l. He now complains of weakness.
Which of the following is likely to explain the above biochemical picture?
1) Addison's Disease
2) Nephrotic syndrome
3) Primary hyperaldosteronism
4) SIADH
5) Diuretic therapy
Answers-5
The long history of his symptoms and serum biochemistry suggests that his condition is due to treatment with frusemide for CCF.
17- A 15-year-old girl was seen by her family physician because of increasing lethargy. She had a recent history of the "flu". Biochemistry tests show that she has renal impairement.
serum sodium 140 mmol/L (137 - 144)
serum potassium 4.2 mmol/L (3.5 - 4.9)
serum urea 28 mmol/L (2.5 - 7.5)
serum creatinine 280 µmol/L (60 - 110)
Her condition does not improve after several weeks on corticosteroid therapy, so a renal biopsy is performed. The biopsy demonstrates the presence of segmental sclerosis of 3 of 10 glomeruli identified in the biopsy specimen. Immunofluorescence studies and electron microscopy do not reveal evidence for immune deposits. What is the most appropriate advice to give regarding her condition?
1) She has an underlying malignancy
2) She may require a renal transplant in 10 years
3) She will improve if she loses weight
4) She will likely develop a restrictive lung disease
5) She will probably improve with additional corticosteroid therapy
Answers-2
The findings point to focal segmental glomerulosclerosis (FSGS), which leads to chronic renal failure in half of cases. The lack of resolution with corticosteroid
therapy and the progression to chronic renal failure is what sets FSGS apart from minimal change disease.
18- Which of the following concerning the pH of urine is correct?
1) is a useful indicator of the acid/base balance of the blood
2) rises on a vegetarian diet
3) is determined by the concentration of ammonium
4) is lower than 5.5 in renal tubular acidosis
5) would be above 7.0 after prolonged and severe vomiting
Answers-2
c - excretion of ammonium occurs when an acid urine is produced but the pH of urine is of course determined by the concentration of H+ ions d-unable to lower
the pH to less than 5.5 in RTA e- This would be expected in an attempt to compensate for the loss of acid however when there is extracellular fluid depletion
the retention of sodium takes priority. Instead of bicarbonate being excreted it is reabsorbed in the proximal and distal nephron and this perpetuates the metabolic
alkalosis until the fluid balance is restored with IV fluids.
19- A young child presents with respiratory distress, worsening over 2 days. Blood gases show a pH of 7.25, a PCO2 of 7.5kPa, a PO2 of 8.5kPa, and a base excess of -4. Which of the following interpretations is correct?
1) Results are consistent with bronchopulmonary dysplasia.
2) Blood gases suggest type 1 respiratory failure.
3) Immediate intubation is required.
4) Results are consistent with late severe asthma.
5) Bicarbonate may be necessary to correct the acidosis.
Answers-4
In interpreting blood gas results, the following sequence may be useful:
Inspect the pH: Is it low, normal or high?
Inspect the CO2: Is it low, normal or high?
Inspect the PO2: Is it low, normal or high?
If the pH is low then an acidosis is present, and inspecting the CO2 will enable you to determine whether this is due to respiratory or metabolic causes. Inspecting the PO2 will tell you whether the child is hypoxic or not. In this case, the pH is reduced, and the CO2 is high, with a base deficit of only -4, insufficient to explain the acidosis from metabolic causes. This is, therefore, a respiratory acidosis, and the PO2 is also a little low suggesting type 2 respiratory failure. Possible causes would include pneumonia, early hyaline membrane disease, ARDS. In asthma, the initial stages show a low CO2, with this climbing only as a pre-terminal event. The results would therefore be consistent with late severe asthma. In bronchopulmonary dysplasia, there is usually long-term CO2 retention with compensatory increase in bicarbonate leading to a positive base excess and normal pH. Bicarbonate is usually only considered if the base deficit exceeds about
-8 or 00.
20 -A 45-year-old solicitor had an onset of severe, crushing, substernal chest pain while attending a football match. He collapsed on his way to the car. Bystander Cardiorespiratory Resuscitation was begun immediately and continued until arrival in Casualty where an endotracheal tube was inserted and ventilation was maintained on 100% oxygen.
Investigations revealed:
pH 7.13
PaO2 560 mmHg
PaCO2 18 mmHg
Bicarbonate 5.8
SaO2 98%
Based on these laboratory values, which of the following statements best describes his current pathophysiology?
1) He is demonstrating a primary respiratory alkalosis
2) He probably developed a large right to left intracardiac shunt
3) His anion gap is probably normal
4) His oxyhemoglobin curve is shifted to the left
5) His pulmonary artery pressure is probably elevated
Answers-5
This young patient with severe central chest pain has probably arrested due to myocardial infarction and arrhythmia. His gases reveal high PO2 following 100%
O2 but severe acidosis due to the arrest and lactic acidosis thus anion gap would be high. He does not have a primary ventilatory failure as his PO2 is high. There is
no left to right shunting and high pulmonary pressures would be expected after this arrest scenario.
21- A 19 year-old female is referred following a visit to the dentist where marked erosion of her teeth was noted. She was entirely asymptomatic and her only medication was the oral contraceptive pill. On examination her blood pressure was 110/70 mmHg and her body mass index was 21.5 kg/m2 (18 - 25).
Investigations
sodium 135 mmol/l
potassium 2.1 mmol/l
bicarbonate 42 mmol/l
urea 2.6 mmol/L
corrected calcium 2.08 mmol/
alkaline phosphatase 201 iu/l (50-110)
What is the most likely diagnosis?
1) Bulimia nervosa
2) Conn's syndrome
3) Laxative abuse
4) Pregnancy
5) Primary hypoparathyroidism
Answers-5
This patient has tooth erosion associated with hypokalaemic metabolic alkalosis and hypocalcaemia. This suggests a diagnosis of hypoparathyroidism. Conn's is unlikely in this age group, is not associated with tooth erosion and hypertension would be expected. Bulimia like laxative abuse would be associated with
hypokalaemia but the hypocalcaemia with raised alkaline phosphatase would not be expected. Early pregnancy would not fit this picture.
22- Which of the following may be responsible for a hypokalaemic hypertension
1) Non-classical congenital adrenal hyperplasia
2) Barter's syndrome
3) Diabetic nephropathy
4) Liddle's syndrome
5) Type IV renal tubular acidosis
Answers-4
Liddle's syndrome is typically asscoiated with hypokalaemic hypertension and low renin and aldosterone concentrations - the so called pseudo-hyperaldosteronism.
Barter's syndrome is associated with hypokalaemia though hypertension is not a feature. In type IV RTA, there is a hyporeninaemic hypoaldosteronism, which may also be produced with diabetic nephropathy. Hence hyperkalaemia is more typical.
23- A 35 year old male presents with weakness and tiredness. He is noted to be hyertensive. Electrolytes show a hypokalaemia and a hypomagnesaemia. What investigation would you select for this patient?
1) Colonoscopy
2) Plasma renin toaldosterone ratio
3) Serum amylase
4) Serum calcium
5) Oral glucose tolerance test
Answers-2
The hypokalaemic hypertension with hypomagnesaemia suggests primary hyperaldosteronism. The most reliable assessment for this would be renin to aldosterone ratio.
24- A 60-year-old man was diagnosed last year with adenocarcinoma of the lung, and a 4 cm mass lesion was treated with a right lower lobectomy. He now has an abdominal CT scan that reveals scattered hepatic mass lesions and hilar lymphadenopathy. For several weeks, he has had increasing malaise. A urinalysis reveals marked proteinuria, and a 24 hour urine protein collection is 2.7 g/24hr. His serum urea is 30 mmol/L (2.5 - 7.5) with creatinine of 450 µmol/L (60 - 110). A renal biopsy is performed, and there is focal deposition of IgG and C3 with a granular pattern. He is most likely to have which of the following conditions?
1) Goodpasture's syndrome
2) Membranous glomerulonephritis
3) Minimal change glomerulonephritis
4) Nodular glomerulosclerosis
5) Rapidly progressive glomerulonephritis
Answers-2
Most cases of membranous GN are idiopathic, but in some patients there is a history of an infection or a malignancy (usually lung) with antigenemia.
25- Which one of the following is true of IgE?
1) Is present in plasma in the same concentration as IgG
2) Is increased acutely in an asthmatic attack
3) Crosses the normal placenta
4) Is increased in the serum of atopic individuals
5) Is involved in type 2 hypersensitivity
Answers-4
IgG is the predominant form of immunoglobulin in plasma at a concentration around 10,000 times that of IgE. IgG crosses the placenta to confer immunity to
the fetus but IgE does not. IgE is involved in arming mast cells and basophils. IgE causes mast cells to release vasoactive amines, such as histamine, producing an inflammatory response which can result in a type I hypersensitivity reaction. IgE is responsible for allergen-mediated diseases such as anaphylaxis, asthma and atopy.
Total serum IgE is frequently increased in those with atopy but serum IgE does not rise acutely during an asthmatic attack.
26- Which of the following features would be expected on lipid analysis in a 57 year old female with two year history of primary biliary cirrhosis?
1) A lipaemic appearance of the serum would be expected.
2) is treated with clofibrate therapy
3) is characteristically associated with tendon xanthomas
4) is characteristically associated with palmar xanthomas
5) No evidence of a dyslipidaemia would be expected with this short a duration of disease
Answers-4
In prolonged cholestasis features include: increased serum cholesterol, a moderate increase in triglyceride, the serum is not lipaemic, and reduced HDL levels. Clinical features include: palmar xanthomas; tuberous xanthomas (particularly on extensor surfaces); tendinous xanthomas are rare. Xanthomas usually only occur if cholestasis has persisted for more than 3 months sometimes fat deposits may involve bone and peripheral nerves.
27- Which of the following is associated with Hyperuricaemia?
1) is usually due to an excess purine consumption
2) occurs in association with acute lymphoblastic leukaemia
3) in primary gout is inherited in an autosomal dominant manner
4) can be reduced with low dose aspirin therapy
5) can be treated with uricosuric drugs even in renal failure
Answers-2
Hyperuricaemia may be due to increased purine intake, urate production or reduced urate clearance, and is most commonly due to the latter. Therefore it can
occur in association with enhanced cell destruction particularly leukaemias. Primary gout has no obvious mode of inheritance, but familial juvenile gouty nephropathy is an autosomal dominantly inherited disorder. Low dose aspirin may exacerbate gout but high dose aspirin is uricosuric. Many of the uricosuric drugs may be detrimental in renal failure and may not be effective.
28- A 53-year-old man presented with hypertension of 150/110 mmHg. He is generally asymptomatic and has no previous medical history of note. He is a smoker of 5 cigarettes daily and drinks modest quantities of alcohol. He takes no prescribed medications. Examination reveals a BMI of 33.5 kg/2 but nil else. The following detail his investigations:
Serum sodium 146 mmol/l (NR 133-145)
Serum potassium 3.2 mmol/l (NR 3.5 - 5)
Urinary potassium excretion 42 mmol/l (NR less than 30)
What is the likely diagnosis?
1) Adrenocortical adenoma
2) Bartter's syndrome
3) Liddle's syndrome
4) Liquorice ingestion
5) Pheochromocytoma
Answers-1
This patient is most likely to have Conn's syndrome as reflected by the hypokalaemic hypertension. Liquorice ingestion or Liddle's syndrome are again possible causes of hypokalaemic hypertension but the question asks for the most likely cause. This is Conn's and is most often caused by an adrenocortical adenoma. Aldosterone promotes active sodium transport and excretion of potassium in the renal tubules (and also sweat glands, salivary glands and colon).
"Clinically, [Primary hyperaldosteronism] Conn's syndrome is characterized by hypertension (often diastolic hypertension), muscular weakness, paresthesias,
headache, polyuria, and polydipsia."
29- Phenytoin:
1) is a benzalkonium Derivative
2) is clinically effective serum level is in the range on 2-10 micrograms/ml.
3) A steady state blood level is achieved by 2-5 days
4) Can be used in management of alchohol withdrawl syndrome
5) Is the drug of choice in absence seizures.
Answers-4
Phenytoin is an imidazolidine derivative.It relates to barbiturates in chemical structure. Clinically effective seum level is in the range on 10-20 micrograms/ml. A
steady state blood level is achieved by 7-10 days.
30 -Which of the following techniques would be most useful in the differential diagnosis between ectopic Cushing's syndrome and pituitary dependent Cushing's disease.
1) Urine free cortisol
2) High dose Dexamethasone suppression test
3) ACTH concentrations
4) Inferior petrosal sinus sampling
5) CRF test
Answers-4
Inferior petrosal sinus sampling with an elevated central ACTH concentration compared with the peripheral value is the most valuable test in the differential
diagnosis of either Cushing's disease or ectopic Cushing's syndrome. The other tests are far less useful in comparison.
31- Hypomagnesaemia may be caused by which of the following drugs?
1) Aminophylline
2) Cisplatin
3) Co-trimoxazole
4) Digoxin
5) Amitriptyline
Answers-2
Thiazide diuretics (not mentioned here) are a common cause of reduced serum magnesium. Cisplatin is a well recognised cause of hypomagnesaemia.
32- Which of the following concerning the conjugation of bilirubin is correct?
1) is catalysed by a glucuronyl transferase
2) occurs in the Kupfer cells of the liver
3) is increased by valproate
4) is inhibited by rifampicin
5) is impaired in Dubin-Johnson syndrome
Answers-1
b - Hepatocytes. c - Enzyme inhibitor. d - Enzyme inducer. e - Conjugation is OK but excretion from the hepatocyte into the bile is impaired. (Gilbert's syndrome -
bilirubin can't Go in to the hepatocyte - unconjugated bilirubinaemia. Crigler-Najjar syndrome - bilirubin can't Conjugate - unconjugated bilirubinaemia. Dubin-Johnson syndrome - bilirubin can't Depart from the hepatocyte - conjugated bilirubinaemia.)
33- Lipoprotein lipase deficiency is associated with:
1) Abetalipoproteinaemia
2) Combined hyperlipidaemia
3) Familial combined hyperlipidaemia
4) Familial Hypercholesterolaemia
5) Marked Hypertriglyceridaemia
Answers-5
Lipoprotein lipase deficiency is autosomal recessive and associated with increased chylomicrons and marked hypertriglyceridaemia.
34- Metabolic alkalosis is characteristically found in which of the following?
1) An infusion of sodium chloride
2) Ileostomy
3) Mineralocorticoid deficiency
4) Pyloric stenosis
5) Salicylate poisoning
Answers-4
Pyloric stenosis is associated with vomiting and the loss of stomach content – hence a metabolic alkalosis. Mineralocorticoid excess (Conn's syndrome) is
associated with a metabolic alkalosis. Ileostomy may be associated with a loss of bicarbonate ions and hence acidosis. Salicylates are themselves acidic and produce a metabolic acidosis. A sodium chloride infusion is neutral and does not alter pH.
35- Which of the following is a recognised feature of abetalipoproteinaemia?
1) a high serum cholesterol
2) palmar xanthomas
3) advanced atherosclerotic vascular disease
4) abnormal red blood cell morphology
5) severe mental retardation
Answers-4
Acanthocytes are seen in abetalipoproteinaemia.
Retinitis pigmentosa is seen in abetalipoproteinaemia. Mental retardation is not present but motor abnormalities and neurodegenerative are seen.
36- An Afro-Carribean male aged 48 years presents with gradual onset of exertional dyspnoea, non productive cough, malaise, weight loss and polyarthralgia. Schirmers test indicates a dry eye. X-ray of the hand shows punched out osteopenic lesions. Which of the following investigation is unlikely to be helpful in establishing the diagnosis of this condition:
1) Serum calcium
2) Serum phosphorus
3) Urea and electrolytes
4) Thallium Scan
5) Quantitative Immunoglobulins.
Answers-4
This condition is sarcoidosis. Serum calcium, Serum phosphorus, Chem7 and Chem 20 and Quantitative Immunoglobulins are all used in establishing the diagnosis.
Gallium scan is helpful in sarcoidosis. (Radiology of extrathoracic sarcoid ...)
Gallium scan vs. Thallium scan.
Gallium scan (radioactive 67Ga) is used to detect inflammation - such as in inflammatory disorders or malignancy.
Thallium (radioactive 201Tl) is a potassium analogue and is used to demonstrate areas of poor perfusion. It is particularly used in cardiology to detect areas of
ischaemia.
37- Polymyalgia rheumatica associated with
1) raised creatinine kinase
2) increased alkaline phosphotase
3) sudden loss of vision in one eye
4) shoulder and pelvic girdle pain in 40 year old man
5) erythema nodosum
Answers-2
Liver enzymes elevated in most patients. Visual disturbances suggestive of temporal arteritis, due to ischaemic changes in ciliary arteries (optic neuritis/infarction) and less commonly due to central artery occlusion. Raised CK in polymyositis. PMR is rare before the age of 50 years.
38- A 73 year old male presented with an acute attack of gout in his left knee.
What is the most likely underlying metabolic cause?
1) decreased renal excretion of uric acid
2) endogenous overproduction of uric acid
3) excessive dietary purine intake
4) lactic acidosis
5) starvation
Answers-1
The aetiology of gout can broadly be divided into cases where there is underexcretion of urate via the kidney (90%) or endogenous overproduction of uric acid (10%) although in practical terms the distinction is rarely made as it allopurinol is the mainstay of long-term treatment (not during the acute attack!) in both groups. In a 73 year old man it is almost certainly reduced renal excretion due to deteriorating renal function and possibly diuretic use. Excessive dietary intake of purines is unlikely to be the main cause in this case.
39- Primary hyperparathyroidism may occur in association with the following conditions
1) Chronic renal failure
2) Vitamin D deficiency
3) Gastrinoma
4) Autoimmune polyendocrine syndrome
5) Sjogren's syndrome
Answers-3
The association of primary hyperparathyroidism and a gastrinoma would suggest a diagnosis of multiple endocrine neoplasia type 1. CRF causes secondary or tertiary hyperparathyroidism, with vit D deficiency causing secondary hyperparathyroidism.
Ther is no association with Sjogren's.
40- With which of the following is hyperprolactinaemia associated?
1) Cabergoline therapy
2) Depression
3) Fluoxetine therapy
4) Hyperthyroidism
5) Sheehan's syndrome
Answers-3
Hyperprolactinaemia may be manifest by a milky discharge from the breasts. Causes include, prolactinoma, hypothyroidism (far increased TRH), Non-functional
tumour with stalk compression and drugs in particular dopamine antagonists such as chlorpromazine, haloperidol and domperidone. Pregnancy is a particularly
common cause of hyperprolactinaemia. Other drugs that are occasionally reported include SSRIs. PCOs is often associated with idiopathic hyperprolactinaemia.
41- Metabolic alkalosis is characteristically found in which of the following?
1) An infusion of sodium chloride
2) Ileostomy
3) Mineralocorticoid deficiency
4) Pyloric stenosis
5) Salicylate poisoning
Answers-4
Pyloric stenosis is associated with vomiting and the loss of stomach content – hence a metabolic alkalosis. Mineralocorticoid excess (Conn's syndrome) is
associated with a metabolic alkalosis. Ileostomy may be associated with a loss of bicarbonate ions and hence acidosis. Salicylates are themselves acidic and produce a metabolic acidosis. A sodium chloride infusion is neutral and does not alter pH.
42- Osteomalacia may be expected in
1) Sarcoidosis
2) Auto-immune adrenalitis
3) Pseudo-hypoparathyroidism
4) Pernicious anaemia
5) Mercury poisoning
Answers-5
Osteomalacia may occur with vitamin D deficiency. Mercury poisoning or any heavy metal poisoning causes an acquired Fanconi syndrome with distal renal tubular acidosis.
43- Which of the following suggests a diagnosis of familial combined hyperlipidaemia (FCHL) rather than heterozygous familial hypercholesterolaemia (FH)?
1) Tendon xanthomas
2) Presence of glucose intolerance
3) Strong family history of premature coronary artery disease
4) Presence of arcus senilus
5) Absence of hyperuricaemia
Answers-2
The genetic dislipidaemias occur in one third of patients who have suffered from their first myocardial infarction below the age of 50 years in men. The commonest is familial combined hyperlipidaemia (two thirds), with a fifth due to familial hypercholesterolaemia. The former can be diagnosed only on family studies, and
there is elevation of fasting plasma tricglycerides not associated with hypercylomicronaemia. It is autosomal dominant, and some family members may have hypercylomicronaemia. Only 20% of children have elevated triglycerides before the age of 25. Obesity, insulin resistance, hyperinsulinaemia, glucose intolerance, and hyperuricaemia are associated. Heterozygous familial hypercholesterolaemia is dominantly inherited, and results from defects in the LDL receptor. The most important clinical manifestation is premature coronary artery disease, particularly with onset between the third or fourth decade. Tendon xanthomata and arcus cornea are rarely present in children, but are very important signs to identify.
44- Which of the following is a characteristic feature of acute intermittent porphyria?
1) autosomal recessive inheritance
2) excessive faecal protoporphyrin excretion
3) excessive urinary porphobilinigoen between acute attacks
4) hypernatraemia during attacks
5) photosensitivity
Answers-3
Features of acute intermittent porphyria include urinary porphobilinogen excretion raised between attacks, hyponatraemia during an acute attack and autosomal
dominant inheritance.
45- Which of the following suggests a diagnosis of Hurler's Syndrome rather than Hunter's Syndrome?
1) X-linked inheritance
2) Mental retardation
3) Skeletal abnormalities
4) Cloudy cornea
5) Cardiomyopathy
Answers-4
Hunter's Syndrome (MPS-2) is of X-linked inheritance. The cornea are clear. The skeletal involvement tends to be mild with no gibbous present, though scoliosis is often found. Mental retardation and heart involvement are less severe than in Hurler's Syndrome. Hurler's Syndrome (MPS0) is autosomal recessive in
inheritance and is associated with cloudy cornea. There is severe mental retardation, and gibbous deformation of the spine is characteristic. There is the
characteristic coarse facies with hepatosplenomegaly.
46 -With respect to lipoprotein transport and metabolism in the body, the following statements are correct EXCEPT:
1) Arterial walls contain cells with LDL receptors.
2) Cholesterol is required for the formation of red blood cell membranes.
3) Chylomicrons are synthesized in the liver.
4) HDL is assembled in the extracellular space.
5) VLDL transformation to LDL occurs in adipose tissue.
Answers-3
Chylomicrons are formed in the gut from exogenous triacylglycerols and cholesterol. They are released into the lymph and thereby enter the blood.They are not formed in the liver.
47- Which of the following conditions may be detectable by growth monitoring?
1) Hyperthyroidism
2) Hypothyroidism
3) Pseudohypoparathyroidism
4) XYY Syndrome
5) Insulin dependent diabetes mellitus
Answers-2
48- Which of the following enzyme defects is associated with a characteristic body odour?
1) Phenylalanine aminotransferase
2) Galactose0-phosphate-uridyltransferase
3) Ornithine transcarbamylase deficiency
4) Fumaryl acetoacetase
5) Branched chain ketoacid decarboxylase
Answers-5
The following inborn errors of amino acid metabolism are associated with abnormal odours: Glutaric acidaemia type II (sweaty feet), hawkinsinuria (swimming pool), isovaleric acidaemia (sweaty feet), maple syrup urine disease (maple syrup), methionine malabsorption (cabbage), multiple carboxylase deficiency (tomcat urine), oasthouse urine disease (hops-like), phenylketonuria (mousy or musty), trimethylaminuria (rotting fish), tyrosinaemia (rancid, fishy or cabbage-like). In addition, ketones may be smelt in diabetic ketoacidosis, and some intermediary disorders of fatty acid metabolism can result in fishy smells.
The general rule is that if a child smells peculiar he requires a metabolic work-up.
49- An 16-year-old man presents with polyuria and polydipsia. Which of the following may confirm the diagnosis of diabetes mellitus?
1) A random plasma glucose of >7.5 mmol/L
2) A finding of 3+ ketonuria
3) An HbA1c of 7.0%
4) A fasting plasma glucose of 7.5 mmol/L
5) An abnormal glucose tolerance test
Answers-4
The diagnosis is usually relatively easy to confirm in a symptomatic subject. A random glucose of >11.1 mmol/L or a fasting glucose of >7.0 mmol/L would be
regarded as confirmatory. There is usually glycosuria in addition to ketonuria.
Isolated ketonuria suggests fasting. A raised glycosolated haemoglobin (HbA1c) is also highly suggestive but not diagnostic. A glucose tolerance test is rarely needed.
50- Which of the following is a characteristic feature of familial hypercholesterolaemia?
1) Autosomal dominant inheritance
2) elevated chylomicrons
3) hypertriglyceridaemia
4) increased expression of LDL receptors
5) Palmar xanthomas
Answers-1
Familial hypercholesterolaemia is an autosomal dominant condition manifest by increased LDL concentrations (not chylomicrons) due to constitutional abnormalities and reduced numbers of the LDL receptor. Hypertriglyceridaemia is not characteristic and HDL concentrations are usually decreased. Tendon xanthomata are characteristic and the condition is associated with a premature cardiovascular mortality.
51- Which of the following has a known association with phenylketonuria?
1) Presentation in the second year of life with absence seizures.
2) The association of red hair and brown eyes.
3) Normal development.
4) Musty odour.
5) Response of some patients to piridoxine.
Answers-4
Phenylketonuria is a quarter as common as congenital hypothyroidism, with an incidence of 1:10,000 live births. It is due either to phenylalanine hydroxylase
deficiency or problems with synthesis or recycling of the bioptrine co-factor. The presentation is with infantile spasms or developmental delay between 6 and 12
months of age. Patients may be musty smelling, fair haired and blue eyed and may develop eczema. Treatment is with restriction of dietary phenylalanine, while
ensuring sufficient for physical and neurological growth. Co-factor defects are treated with a diet low in phenylalanine and high in neurotransmitter precursors.