Flashcards in Chemical Pathology Deck (80)
what is the enzyme missing in lesch nyhan
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.
what is high CRP a risk factor for
what can be broken down to make amino acids
high fluid intake as a baby can be a risk factor for what
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.
how do you calculate the osmolarity
2(sodium + potassium) + urea + glucose
normal osmolarity? what does it help diagnose
serum = 275-295 it is used to diagnose SIADH
At what point should you treat the hyponatraemia rather than the underlying cause?
when drops below 125.
What hapens when sodium falls?
N+v - 136
confusion - 131
seizures - pulmonary odema (non cardio) - 125
coma - 117
What is TURP syndrome
water is absorbed through damaged prostate and causes hypoonatraemia
How do you differentiate true hyponatraemia from other causes?
HIGH - glucose/mantiol or infusion
NORMAL - spurious, drip arm sample, paraproteinaemia/hyperlipidaemia
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)
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
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
4 causes of SIADH
drugs - SSRI, carbamazepine, opiates.
What happens with rapid correction of HYPERnatraemia
occurs in ITU patients
thirst confusion, ataxia,
What happens with rapid correction of HYPERnatraemia >148mmol/l
occurs in ITU patients
thirst confusion, ataxia, seizures, coma.
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
What is the normal range of potassium
What causes tall tented t waves
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.
What are the causes of hypokalaemia?
ANYTHING WHICH Increases LEVEL OF SODIUM REACHING THE DISTAL NEPHRON
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
How do you diagnose conns
renin aldosterone ratio.
Renin should be low
When you are acidotic you are____kalaemic
Which tranporter is defective in barrters sydrome
triple (permanent frusemide
which transporter is blocked in gitelman syndrome
NaCl like having a permanent thiazide diuretic
What are the causes of hyperkalaemia?
low insulin - DKA
tissue damage - crush injury or haemolysis for example from a prosthetic heart valve.
low aldosterone - adisons
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.
How does addisons present?
acutely abdominal pain, hypotensive shock
low grade fever.
lack of ADH. causes hypernatraemia due to loss of primarily water.