Hydrochlorothiazide: Blood chemistry effects


Hydrochlorothiazide is a thiazide class diuretic that works by inhibiting the kidney’s ability to retain water. It is also thought to directly decrease peripheral vascular resistance via another mechanism.

Specifically, thiazides inhibit sodium reabsorption at the distal convoluted tubule, promoting naturesis and water loss. Like loop diuretics (which block reabsorption in the ascending tubule) potassium excretion is increased. Thiazides also promote calcium reabsorption at the same site via an unrelated mechanism. Since calcium and magnesium are opposing cations in the plasma, you can get hypomagnesia.

Thiazide diuretics also decrease glucose tolerance for unclear reasons, perhaps due to reduced insulin secretion. Hyperglycemia occurs and is reduced when K+ supplementation is given with a thiazide.

Thiazides may increase LDL cholesterol levels, total cholesterol, and triglycerides.

Effect of Hydrochlorothiazide

  • Decreased: sodium, potassium, magnesium
  • Increased: calcium, glucose, LDL, TC, TG


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See Also:

ABA:HCTZ – mechanism of action