Thiazide increases serum calcium in anuric patients: the role of parathyroid hormone.
We evaluated the effect of hydrochlorothiazide in a sample of anuric patients on hemodialysis and found an increase in serum calcium, which occurred only in those with parathyroid hormone >300 pg/ml. This finding highlights the extra-renal effect of this diuretic and a possible role of parathyroid hormone in the mechanism.


OBJECTIVE
Thiazide diuretics are commonly used in patients with chronic kidney disease to treat hypertension. Their effects on calcium and bone metabolism are not well established, once calciuria may not fully explain levels of calcium and parathyroid hormone (PTH) in this population. A previous study has suggested that thiazides require the presence of PTH as a permissive condition for its renal action. In anuric patients, however, the role of PTH, if any, in the thiazide effect is unknown.


METHODS
To assess thiazide extra renal effect on serum calcium and whether such an effect is reliant on PTH, hydrochlorothiazide (HCTZ) 100 mg was given orally once a day to a sample of 19 anuric patients on hemodialysis for 2 weeks. Laboratories' analyses were obtained in three phases: baseline, after diuretic use, and after a 2-week washout phase.


RESULTS
We demonstrated that serum calcium (Ca) increased in ten patients (52.6%) after HCTZ use, returning to previous levels after the washout period. Out of the 19 patients, ten presented PTH ≥ 300 pg/ml, and Ca has increased in eight of them, whereas in the other nine patients with PTH < 300 pg/ml, serum Ca has increased only in two individuals (RR risk of increase Ca 3.9; p = 0.012).


CONCLUSIONS
HCTZ was capable of increasing serum Ca in a sample of anuric patients on hemodialysis and seems this effect is highly dependent on PTH levels. Caution is required while interpreting this result, as the small sample size might implicate in a finding caused by chance.
Department of Medicine, Renal Division, Hospital das Clinicas, Universidade de São Paulo, São Paulo, Brazil. raquelfvvasco@gmail.com.
Raquel F V
RFV
Vasco
Hospital das Clinicas, Pharmacy Division, Universidade de São Paulo, São Paulo, Brazil.
Eduardo T
ET
Reis
Department of Medicine, Renal Division, Hospital das Clinicas, Universidade de São Paulo, São Paulo, Brazil.|Universidade Nove de Julho, UNINOVE, São Paulo, Brazil.
Rosa M A
RMA
Moyses
Department of Medicine, Renal Division, Hospital das Clinicas, Universidade de São Paulo, São Paulo, Brazil.
Rosilene M
RM
Elias
D000328:Adult; D001002:Anuria / Q000097:blood* / Q000188:drug therapy*; D002118:Calcium / Q000097:blood*; D005260:Female; D006801:Humans; D006852:Hydrochlorothiazide / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D006435:Renal Dialysis; D049993:Sodium Chloride Symporter Inhibitors / Q000494:pharmacology*; D016896:Treatment Outcome
D010281:Parathyroid Hormone; D049993:Sodium Chloride Symporter Inhibitors; D006852:Hydrochlorothiazide; D002118:Calcium
Calcium; Diuretic; Hemodialysis; Hydrochlorothiazide; Parathyroid hormone