Short-term propofol sedation increases serum levels of parathyroid hormone independent of calcium levels in normal subjects
© The Author(s) 2001
Received: 15 January 2001
Published: 2 March 2001
Propofol (Diprivan®, AstraZeneca) is a surgical anesthetic and an intensive care sedative that contains 0.005% disodium edetate (EDTA) as an antimicrobial agent. EDTA is also a chelating agent that may affect the function of the parathyroid-calcium axis, predisposing patients to the development of hypocalcemia.
To compare the effect of propofol with and without EDTA on the parathyroid-calcium axis in normal healthy volunteers.
In a randomized, double-blind, age-stratified, crossover trial, 50 normal subjects were randomly treated with propofol or propofol EDTA as a bolus containing 2 mg propofol/kg iv (1 mg/kg if aged > 65 years), followed by randomly selected infusions (25, 50, 100, or 200 μg/kg per min). The alternate treatment was given 15 to 29 days later. Changes in ionized Ca, total Mg, and intact parathyroid hormone (PTH) levels were measured. The normal range for PTH is 9 to 46 pg/ml.
Eighteen women and 32 men were equally distributed among 3 age groups (19–34, 35–65, > 65 years). Ionized Ca and total Mg remained within the normal range for both treatments throughout the study. However, PTH levels significantly increased from baseline (40.7 ± 19.8 pg/ml and 40.4 ± 16.7 pg/ml for propofol and propofol EDTA, respectively) to 54.3 ± 24.7 pg/ml and 55.8 ± 23.0 pg/ml, respectively, (P < 0.05) 4 min after the bolus injection and returned to baseline within 60 min. Propofol infusions significantly (P < 0.05) increased PTH levels in a stepwise fashion. PTH levels increased 31% and 43% for the 100 and 200 μg/kg per min infusions of propofol, respectively. These PTH levels are similar to those seen in hyperparathyroidism and hypocalcemia. Age did not affect PTH responses.
Propofol was associated with a dose-dependent increase in PTH levels that were not related to changes in ionized Ca, total Mg, or EDTA.