BIOCHEMISTRY

Question 1

What does VIPoma cause?

Answer 1

Excessive loss of potassium and bicarbonates through excessive secretory diarrhoea (pancreatic cholera) => hypokalaemia + metabolic acidosis + raised urea + hypercalcaemia + hyperchloraemia

Question 2

What does Pyloric stenosis cause?

Answer 2

Hypokalaemic hypochloraemic metabolic alkalosis + paradoxical aciduria

Question 3

What is the pH of normal saline?

Answer 3

5 (may cause mild metabolic acidosis with significant infusions)

Question 4

What acid-base disturbance is associated with Ileostomy?

Answer 4

Acidosis through loss of bicarbonate ions

Question 5

What acid-base disturbance is associated with mineralocorticoid excess (Conn’s syndrome) ?

Answer 5

Metabolic alkalosis

Question 6

What drugs lead to hyperkalaemia?

Answer 6

• Potassium sparing diuretics
• NSAIDs
• ACE inhibitors
• Cyclosporin
• Beta-blockers

Question 7

ECG changes in hypokalaemia?

Answer 7

U waves, ST-depression, low-amplitude T-wave, Ventricular fibrillation

Question 8

ECG changes in hyperkalaemia?

Answer 8

Tall tented T-waves, absent p waves, asystole, Ventricular fibrillation, QRS widening in levels >7

Question 9

What is Gaucher’s disease?

Answer 9

Lysosomal storage disease common in Ashkenazi jews - Deficit in Lysosomal Hydrolase Beta-Glucosidase deficiency

Question 10

What is Tay-Sachs disease?

Answer 10

It’s a fatal lysosomal storage disease that results in the destruction of nerve cells in the brain and spinal cord due to Hexosaminidase A deficiency

Question 11

What is Niemann-Pick diease?

Answer 11

AKA Acid Sphingomyelinase deficiency => excess accumulation of fats (sphingomyelin++) within lysosomes

Question 12

What are causes of decreased uric acid excretion?

Answer 12

• Acute or chronic renal disease
• Drugs: Aspirin and thiazides
• Down syndrome
• Lead poisoning

Question 13

Young male + lower back pain due to vertebral collapse = diagnosis and investigation?

Answer 13

Osteoporosis - Check testosterone levels

Question 14

What type of stones appear in acidic urine?

Answer 14

Uric acid stone (acid in acid)

Question 15

What type of stones appear in alkaline urine?

Answer 15

Calcium phosphate stone (alKALine=KALcium)

Question 16

Mode of inheritance of Phenyketonuria?

Answer 16

Autosomal recessive

Question 17

Genetic defect in Phenylketonuria?

Answer 17

Deficit in Phenylalanine hydroxylase (Chromosome 12) or tetrahybdobiopterin (chromosomes 4 and 10)

Question 18

Features of Phenylketonuria?

Answer 18

Microcephaly, prominent maxilla, growth retardation, wide-spaced teeth, learning difficulties

Question 19

Diagnosis of Phenylketonuria?

Answer 19

• Raised Phenylalanine levels
• Increased urinary Phe metabolites
• Normal cofactor (tetrahybdobiopterin) levels

Question 20

What enzyme is responsible for catalysing bilirubin conjugation?

Answer 20

Glucuronyl transferase

Question 21

What conditions result from absence of glucuronyl transferase?

Answer 21

Criggler-Najjar (significantly low levels) and Gilbert’s syndrome (less significant reduction) => Unconjugated bilirubinaemia

Question 22

What biochemical disturbance is seen in Dublin-Johnson syndrome?

Answer 22

Conjugated bilirubin (the defect is not in Glucuronyl transferase, but in excretion)

Question 23

What is the role of microtubules?

Answer 23

Involved in mitotic processes and intracellular transportation

Question 24

High or normal PTH + hypercalcaemia = diagnosis?

Answer 24

Hyperparathyroidism

Question 25

What are Anti-mitochondrial antibodies targeted at?

Answer 25

Pyruvate dehydrogenase (present in mitochondria, hence the name AMA)

Question 26

Where in the cell does glycolysis take place?

Answer 26

Cytosol

Question 27

How to diagnose Lactose Intolerance?

Answer 27

Methane breath test - May also be diagnosed by DNA assay of the lactase gene along with a hydrogen breath test

Question 28

Management of lactose intolerance?

Answer 28

Careful replacement of Lactase

Question 29

What is the correct dose of Vitamin D supplementation?

Answer 29

800 UI/day