Can Hydrochlorothiazide (HCTZ) cause hypokalemia?

From the Guidelines

Hydrochlorothiazide (HCTZ) can cause hypokalemia, a lower than normal potassium level in the blood, as it increases potassium excretion in the urine, leading to potassium depletion. This is one of the most common side effects of this medication. HCTZ is a thiazide diuretic that works by increasing the excretion of sodium and water through the kidneys, which helps reduce blood pressure.

Key Points to Consider

• Typically, potassium levels should be monitored when starting HCTZ therapy, especially at higher doses (such as 25-50 mg daily) 1.
• Patients taking HCTZ may need to increase their dietary potassium intake by consuming foods rich in potassium like bananas, oranges, and leafy greens, or they might require potassium supplements in some cases.
• Symptoms of hypokalemia include muscle weakness, cramps, fatigue, and in severe cases, cardiac arrhythmias.
• Combining HCTZ with potassium-sparing diuretics like spironolactone can help mitigate this effect when necessary.

Monitoring and Prevention

• It is essential to monitor renal function and electrolytes when using HCTZ, especially in elderly patients or those with a history of gout, diabetes, hyperlipidaemia, or CrCL <30 mL/min 1.
• Caution should be exercised in patients with poor mobility, urinary incontinence, AKI, and electrolyte disturbances.
• Avoid excessive diuresis in elderly patients with HFpEF.

Recommendation

To minimize the risk of hypokalemia, it is recommended to monitor potassium levels regularly and adjust the treatment plan as needed, considering the use of potassium-sparing diuretics or supplements if necessary. This approach can help mitigate the risk of hypokalemia and ensure the safe use of HCTZ in patients with hypertension.

From the FDA Drug Label

In published studies, clinically significant hypokalemia has been consistently less common in patients who received 12. 5 mg of hydrochlorothiazide than in patients who received higher doses. Hypokalemia may develop, especially with brisk diuresis when severe cirrhosis is present, during concomitant use of corticosteroid or adrenocorticotropic hormone (ACTH) or after prolonged therapy. Interference with adequate oral electrolyte intake will also contribute to hypokalemia Hypokalemia and hypomagnesemia can provoke ventricular arrhythmias or sensitize or exaggerate the response of the heart to the toxic effects of digitalis. Hypokalemia may be avoided or treated by potassium supplementation or increased intake of potassium rich foods Corticosteroid, ACTH – intensified electrolyte depletion, particularly hypokalemia. The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias.

Yes, hydrochlorothiazide can cause hypokalemia. This is particularly likely in certain situations, such as:

• With high doses of the medication
• When used with other medications like corticosteroids or adrenocorticotropic hormone (ACTH)
• In patients with severe cirrhosis
• After prolonged therapy
• When there is interference with adequate oral electrolyte intake 2, 2.

From the Research

Hydrochlorothiazide and Hypokalemia

• Hydrochlorothiazide (HCTZ) is a thiazide diuretic commonly used to treat hypertension, but it is associated with a well-recognized adverse effect: hypokalemia (low serum potassium levels) 3, 4, 5, 6, 7.
• Studies have shown that the use of HCTZ can lead to hypokalemia, with a prevalence ranging from 7% to 56% in patients taking thiazide diuretics 6.
• Factors that increase the risk of hypokalemia in HCTZ users include:
  • Demographics: women, non-Hispanic blacks, and underweight individuals 3.
  • Prescription patterns: monotherapy, long-term therapy, and high doses of HCTZ 3, 5, 7.
  • Dietary factors: low consumption of dietary potassium 4.

Clinical Manifestations and Diagnosis

• Hypokalemia can be asymptomatic or present with non-specific symptoms, making diagnosis based on serum potassium levels and ECG findings crucial 4, 6.
• The occurrence of premature ventricular contractions (PVCs) correlates significantly with the decrease in serum potassium levels during HCTZ therapy 5, 7.

Management and Prevention

• Reducing the dose of HCTZ and potassium supplementation are effective therapies for hypokalemia 6.
• Combining HCTZ with a potassium-sparing diuretic or blocker of the renin-angiotensin system can reduce the risk of hypokalemia 3, 6.
• Lifestyle modifications, such as lowering salt intake and increasing consumption of vegetables and fruits, can help reduce blood pressure and prevent hypokalemia 6.