clinical sciences

Question 1

SIADH

Answer 1

aquaporin 2 insertion in collecting ducts

more reabsorption of sodium and water

Question 2

specificity =

Answer 2

true negatives/ TN + false positives

Question 3

sensitivity

Answer 3

true positives/ TP + false negatives

Question 4

viral meningitis Rx

Answer 4

nil

encephalitis requires treatment not meningitis

Question 5

Hyponatraemia

Urinary sodium <20

Answer 5

Sodium depletion, extra-renal loss
diarrhoea, vomiting, sweating
burns, adenoma of rectum

Water excess (patient often hypervolaemic and oedematous)
secondary hyperaldosteronism: heart failure, liver cirrhosis
reduced GFR: renal failure
IV dextrose, psychogenic polydipsia

Question 6

Hyponatraemia

Urinary Sodium >20

Answer 6

Sodium depletion, renal loss (patient often hypovolaemic)
diuretics: thiazides, loop diuretics
Addison’s disease
diuretic stage of renal failure

Patient often euvolaemic
SIADH (urine osmolality > 500 mmol/kg)
hypothyroidism

Question 7

Vitamin D-resistant rickets

Answer 7

X-linked dominant condition which usually presents in infancy with failure to thrive. It is caused by impaired phosphate reabsorption in the renal tubules

Features
failure to thrive
normal serum calcium, low phosphate, elevated alkaline phosphotase
x-ray changes: cupped metaphyses with widening of the epiphyses

Diagnosis is made by demonstrating increased urinary phosphate

Management
high-dose vitamin D supplements
oral phosphate supplements

Question 8

horseshoe kidney

Answer 8

turner’s syndrome

Question 9

X linked recessive

Answer 9

Androgen insensitivity syndrome
Becker muscular dystrophy
Colour blindness
Duchenne muscular dystrophy
Fabry's disease
G6PD deficiency
Haemophilia A,B
Hunter's disease
Lesch-Nyhan syndrome
Nephrogenic diabetes insipidus
Ocular albinism
Retinitis pigmentosa
Wiskott-Aldrich syndrome

Question 10

ejection fraction is

Answer 10

Stroke volume / end diastolic LV volume

Question 11

Case-control study -

Answer 11

compares a group with a disease to a group without, looking at past exposure to a possible causal agent for the condition

Question 12

Likelihood ratio for a positive test result

Answer 12

= sensitivity / (1 - specificity)

Question 13

Congenital toxoplasmosis

Answer 13

cerebral calcification

chorioretinitis

Question 14

Positive predictive value =

Answer 14

TP / (TP + FP)

Question 15

Likelihood ratio for a negative test result

Answer 15

(1 - sensitivity) / specificity

Question 16

non inferiority needs

Answer 16

smaller sample size

Question 17

Hypokalaemia with alkalosis

Answer 17

vomiting
thiazide and loop diuretics
Cushing’s syndrome
Conn’s syndrome (primary hyperaldosteronism)

Question 18

Hypokalaemia with acidosis

Answer 18

diarrhoea
renal tubular acidosis
acetazolamide
partially treated diabetic ketoacidosis

Question 19

Fragile X syndrome

Answer 19

Fragile X syndrome is a trinucleotide repeat disorder.

Features in males
learning difficulties
large low set ears, long thin face, high arched palate
macroorchidism
hypotonia
autism is more common
mitral valve prolapse

Features in females (who have one fragile chromosome and one normal X chromosome) range from normal to mild

Diagnosis
can be made antenatally by chorionic villus sampling or amniocentesis
analysis of the number of CGG repeats using restriction endonuclease digestion and Southern blot analysis

Question 20

Turner’s 45X

Answer 20

short stature
shield chest, widely spaced nipples
webbed neck
bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
primary amenorrhoea
cystic hygroma (often diagnosed prenatally)
high-arched palate
short fourth metacarpal
multiple pigmented naevi
lymphoedema in neonates (especially feet)
gonadotrophin levels will be elevated
hypothyroidism is much more common in Turner’s
horseshoe kidney: the most common renal abnormality in Turner’s syndrome

Question 21

congenital adrenal hyperplasia causes what metabolic disorder

Answer 21

metabolic alkalosis

Question 22

high cell count can cause

Answer 22

pseudohyperkalaemia

Question 23

Normal distribution

Answer 23

68. 3% of values lie within 1 SD of the mean
69. 4% of values lie within 2 SD of the mean
70. 7% of values lie within 3 SD of the mean

Question 24

endothelin (vasoconstrictor)

Answer 24

Promotes release
angiotensin II
ADH
hypoxia
mechanical shearing forces

Inhibits release
nitric oxide
prostacyclin

Raised levels in
MI
heart failure
ARF
asthma
primary pulmonary hypertension

Question 25

Power

Answer 25

= 1 - the probability of a type II error

type 2 error is when null hypothesis is accepted when it’s false