Metabolic medicine Flashcards
Features of hypocalceaemia?
tetany: muscle twitching, cramping and spasm
perioral paraesthesia
if chronic: depression, cataracts
ECG: prolonged QT interval
The initial management of hypercalcaemia
rehydration with normal saline, typically 3-4 litres/day. Following rehydration bisphosphonates may be used. They typically take 2-3 days to work with maximal effect being seen at 7 days
Causes of hypocalcaemia?
vitamin D deficiency (osteomalacia)
chronic kidney disease
hypoparathyroidism (e.g. post thyroid/parathyroid surgery)
pseudohypoparathyroidism (target cells insensitive to PTH)
rhabdomyolysis (initial stages)
magnesium deficiency (due to end organ PTH resistance)
massive blood transfusion
acute pancreatitis
What is type 1 RTA?
Inability to generate acid urine (secrete H+) in distal tubule
causes hypokalaemia
complications include nephrocalcinosis and renal stones
causes include idiopathic, rheumatoid arthritis, SLE, Sjogren’s, amphotericin B toxicity, analgesic nephropathy
Type 2 RTA?
decreased HCO3- reabsorption in proximal tubule
causes hypokalaemia
complications include osteomalacia
causes include idiopathic, as part of Fanconi syndrome, Wilson’s disease, cystinosis, outdated tetracyclines, carbonic anhydrase inhibitors (acetazolamide, topiramate)
What is type 3 RTA?
extremely rare
caused by carbonic anhydrase II deficiency
results in hypokalaemia
What is type 4 RTA?
reduction in aldosterone leads in turn to a reduction in proximal tubular ammonium excretion
causes hyperkalaemia
causes include hypoaldosteronism, diabetes
What kind of drug is indapamide?
Thiazide like diuretic
ECG changes in hyperkalaemia?
- Low flat P waves
- Broad bizarre QRS
- Slurring into the ST segment
- Tall tented T waves
Management of SIADH?
correction must be done slowly to avoid precipitating central pontine myelinolysis
fluid restriction
demeclocycline: reduces the responsiveness of the collecting tubule cells to ADH
ADH (vasopressin) receptor antagonists have been developed
Drugs causing SIADH?
sulfonylureas*
SSRIs, tricyclics
carbamazepine
vincristine
cyclophosphamide
Management of hypercalacaemia?
rehydration with normal saline, typically 3-4 litres/day. Following rehydration bisphosphonates may be used. They typically take 2-3 days to work with maximal effect being seen at 7 days
Cause of hyperkalaemia?
acute kidney injury
drugs*: potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, heparin**
metabolic acidosis
Addison’s disease
rhabdomyolysis
massive blood transfusion
What is importnat to look at when looking at serum and urine osmolarity?
Subjectively is the result inappropriately high for the sodium levels?
Management of Patients with acute, severe (<120 mmol/L) or symptomatic hyponatraemia
Hypertonic saline (typically 3% NaCl)
