Clinical features of hypokalemia

Prominent effects of hypokalemia is on heart, skeletal, and intestinal muscle cells.

Effect of hypokalemia on the heart

Hypokalemia is a major risk factor for both ventricular and atrial arrhythmias.

It predisposes to digoxin toxicity 

Electrocardiographic changes in hypokalemia are the following.

Broad flat T waves, 

ST depression, 

QT prolongation

These finding are most marked when serum K + is <2.7 mmol/L.

 Effect of hypokalemia on skeletal muscle

Hypokalemia will results in hyperpolarization of skeletal muscle, hence impairing the capacity to depolarize and contract the skeletal muscle which results in weakness and even paralysis . Hypokalemia can causes skeletal myopathy and predisposes to rhabdomyolysis.

Effect on intestinal smooth muscle

The paralytic effects of hypokalemia on smooth muscle of intestine  may result in intestinal ileus.

The functional effects of hypokalemia on the kidney include

Na + -Cl – and HCO 3 - retention

Polyuria 

Phosphaturia 

Hypocitraturia

Activation of renal ammoniagenesis. 

Retention of bicarbonate and change in other acid-base effects of hypokalemia can predispose to metabolic alkalosis.Polyuria is due to both polydipsia and an AVP-resistant renal concentrating

defect.

Hypokalemia can cause structural changes in the kidney which include 

1.Relatively specific vacuolizing injury to proximal renal tubular cells

2.Interstitial nephritis

3.Renal cysts. 

4.Hypokalemia can also predisposes to acute injury to kidney so lead to end-stage renal disease

This is commonly seen in those patients with long-standing hypokalemia due to laxative abuse or eating disorders

Hypokalemia and/or decreased dietary K +intake is implicated in the pathophysiology as well as in the progression of hypertension, heart failure, and stroke.If there is short-term K + restriction in healthy humans and in patients with essential hypertension that will lead to result in Na + -Cl – retention and hypertension. Correction of hypokalemia is required in hypertensive patients treated with diuretics, because correction of hypokalemia helps to control blood pressure.

Signs and Symptoms of Hypokalemia

1. Alkalosis
2. Shallow Respirations 
3. Irritability
4. Confusion and drowsiness
5. Weakness and fatigue
6. Arrhythmias
7. Lethargy
8. Thready Pulse