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Flashcards in Chemical Pathology Deck (80)
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1

what is the enzyme missing in lesch nyhan

HGPRT

2

How can one categorise the causes of a raised urate (in gout)

Increased production and decreased clearance

P: myeloproliferative, lymphoproliferative, chronic HA

C: drugs(aspirin and thiazides, lead) CKD or barterrs, downs syndrome.

3

what is high CRP a risk factor for

cardio problems

4

what can be broken down to make amino acids

albumin

5

high fluid intake as a baby can be a risk factor for what

NEC

6

What is the difference between osmolality and osmolarity

LAL is in kg
LAR is in litres

they are very similar but the difference is known as the osmolar gap.

7

how do you calculate the osmolarity

2(sodium + potassium) + urea + glucose

8

normal osmolarity? what does it help diagnose

serum = 275-295 it is used to diagnose SIADH

9

At what point should you treat the hyponatraemia rather than the underlying cause?

when drops below 125.

10

What hapens when sodium falls?

N+v - 136
confusion - 131
seizures - pulmonary odema (non cardio) - 125
coma - 117

11

What is TURP syndrome

water is absorbed through damaged prostate and causes hypoonatraemia

12

How do you differentiate true hyponatraemia from other causes?

osmolality.

HIGH - glucose/mantiol or infusion
NORMAL - spurious, drip arm sample, paraproteinaemia/hyperlipidaemia

13

how do you diagnose Adrenal insufficiency

ADDISONS DISEASE - 85%(but not so in the rest of the world) (automimmune)
true hyponatraemia with euvolemia and therefore high urinary sodium (>20)
HIGH POTASSIUM

other causes of adrenal insufficiency include:
TB and other infections
anything interfering with hypothamic axis to prevent release of CRH

SHORT SYNACTHen test to diagnose. there will be no rise in cortisol seen

14

How do you diagnose SIADH

urine osmolarity is high but serum is low as it is a TRUE hyponatraemia
it is a diagnosis of exclusion

15

4 causes of SIADH

brain insult
lung pathology
malignancy
drugs - SSRI, carbamazepine, opiates.

16

What happens with rapid correction of HYPERnatraemia

cerebral odema
occurs in ITU patients

sx include:
thirst confusion, ataxia,

17

What happens with rapid correction of HYPERnatraemia >148mmol/l

cerebral odema
occurs in ITU patients

sx include:
thirst confusion, ataxia, seizures, coma.

18

What would you see on results of psychogenic polydipsia

nothing abnormal, merely symptoms of dry mouth and thirst. often accompied by psychological disease such as schizophrenia

19

What is the normal range of potassium

3.5-5.5

20

What causes tall tented t waves

hyperkalaemia

21

in what way are potassium and hydrogen linked?

every time you drop 0.1 in pH your potassium will go up by 0.7

they work in opposites.

22

What are the causes of hypokalaemia?

ANYTHING WHICH Increases LEVEL OF SODIUM REACHING THE DISTAL NEPHRON

GI loss

Renal Loss - high aldosterone, osmotic diuresis - diabetes.

redistribution into cells - insulin causes entry into vcells as do beta agonsists and an alkalosis

rare causes - renal tubular acidosis
barterr
gitelman

23

How do you diagnose conns

primary hyperaldosteronism

renin aldosterone ratio.

Renin should be low

24

When you are acidotic you are____kalaemic

HYPER

25

Which tranporter is defective in barrters sydrome

triple (permanent frusemide

26

which transporter is blocked in gitelman syndrome

NaCl like having a permanent thiazide diuretic

27

What are the causes of hyperkalaemia?

TRANSCELLULAR MOVEMENT
acidosis
low insulin - DKA
tissue damage - crush injury or haemolysis for example from a prosthetic heart valve.

DECREASED EXCRETION:
low aldosterone - adisons
spironolactone
Acute oliguric renal failure and end stage chronic renal failure
NSIADS and ace inihibitors reduce renin levels and therefore aldosterone.

artifactual: delayed separation - if they say the porters are on strike

also haemolysis is artifactual.

28

How does addisons present?

acutely abdominal pain, hypotensive shock

fatigue
weakness
nausea
vomiting
low grade fever.
CONFUSION

29

Diabetes insipidus

lack of ADH. causes hypernatraemia due to loss of primarily water.

30

3 causes of euvolemic hyponatraemia

SIADH
hypothyroidism
adrenal insufficiency