severe (GFR < 10ml/min) or when a defect in tubular excretion is present,
as in salt-depletion, mineralocorticoid deficiency, drug interference or
renal tubular disease.
Hyporeninaemic hypoaldosteronism is a common cause of
hyperkalaemia in diabetics. This is seen usually in elderly diabetic with
mild renal impairment, hyperkalaemia is mild (K= 5.5-6.5), the condition
is aggravated by hyperglycaemia and/or salt depletion.
Clinical features of hyperkalaemia:
These are due to the effect of hyperkalaemia on cell membrane
excitability especially those of the heart and the neuromuscular junctions.
The toxic effect of K+ depends on the rate of development and severity of
hyperkalaemia. In patients with chronic renal failure, since the
development is usually very slow, there will be a cell membrane
adaptation and toxicity to occur needs relatively very high level in
comparison with that occurring with acute renal failure.
The manifestations include tingling, numbness, circumoral
paraesthesia, muscle weakness with loss of tendon reflexes. The more
serious, which can even be the first to appear, is the cardiac toxicity.
ECG tracing in hyperkalaemic patient may show:
- Tall T waves
- Prolongation of the PR interval
- Widening of the QRS complex
- Finally cardiac arrest in diastole
Treatment: