Gout is a Relative Contraindication to Thiazide Diuretics
The correct answer is A. Gout. According to the 2007 European Society of Hypertension (ESH) and European Society of Cardiology (ESC) guidelines, gout is explicitly listed as a compelling contraindication to the use of thiazide diuretics 1.
Mechanism and Evidence
Thiazide diuretics can cause hyperuricemia through several mechanisms:
- They compete with uric acid for renal tubular secretion
- They cause volume contraction which reduces uric acid excretion
- At doses of ≥50 mg/day of hydrochlorothiazide or ≥25 mg/day of chlorthalidone, the risk of hyperuricemia increases significantly 1
The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) confirms that "uric acid will increase in many patients receiving a diuretic" 1. While the JNC 7 notes that "the occurrence of gout is uncommon with dosages ≤50 mg/d of hydrochlorothiazide or 25 mg of chlorthalidone," the risk remains present, particularly in predisposed individuals.
Why Other Options Are Not Correct
B. Hyperkalemia: Thiazide diuretics typically cause hypokalemia, not hyperkalemia. They would actually be beneficial in patients with hyperkalemia.
C. Peripheral vascular disease: There is no evidence in the guidelines that peripheral vascular disease is a contraindication to thiazide diuretics. In fact, thiazides are often used in patients with cardiovascular conditions.
D. Heart block: Heart block is listed as a contraindication to beta-blockers, not thiazide diuretics 1. Thiazide diuretics do not significantly affect cardiac conduction.
Clinical Considerations When Using Thiazide Diuretics
Appropriate Use
- Thiazides remain first-line agents for hypertension management 1
- They are particularly effective in low-renin patient groups (e.g., Black patients, elderly, and those with diabetes) 2
- Chlorthalidone may be preferred over hydrochlorothiazide due to its longer half-life (40-60 hours) and more consistent 24-hour blood pressure control 2
Other Relative Contraindications
- Metabolic syndrome (possible contraindication) 1
- Glucose intolerance (possible contraindication) 1
- Pregnancy (possible contraindication) 1
Monitoring Recommendations
- Serum uric acid levels should be monitored, especially in patients with a history of gout
- Potassium levels should be checked regularly due to risk of hypokalemia
- Blood glucose should be monitored as thiazide-induced hypokalemia is associated with increased blood glucose 2
Special Situations
In patients with advanced chronic kidney disease (CKD), thiazide diuretics are traditionally considered ineffective when eGFR is <30 mL/min/1.73 m². The ESC guidelines for heart failure specifically state: "In patients with a creatinine clearance <30 mL/min, thiazide diuretics are ineffective and loop diuretics are preferred" 1.
However, for patients who need a thiazide diuretic despite having gout, concomitant use of a uric acid-lowering drug such as allopurinol may be considered to mitigate the risk 2.
In summary, while thiazide diuretics are valuable antihypertensive medications, their use requires careful consideration of the patient's comorbidities, with gout being a significant relative contraindication due to the drugs' effect on uric acid metabolism.