Blood Pressure and Serum Parathyroid Hormone Level

To the Editor In their Research Letter testing the hypothesis of an association between diuretic use and elevated serum parathyroid hormone (PTH) levels in adults with normal renal function, Corapi et al¹ state that their findings demonstrate that loop use is associated with higher PTH level, even after adjustment for potential confounders. Of note, the authors did not include blood pressure as a covariate in their multivariable model. Although heart failure—included in the multivariable analysis—is one of its main indications, loop diuretics are not exclusively used for this condition and have been shown to achieve a good response as combination therapy in patients with resistant hypertension.² Moreover, a history of hypertension is common in patients with heart failure, especially in those with preserved left ventricular systolic function.²