1. The effect of terbutaline infusion over 4 h on serum levels of potassium, ionized calcium, phosphate and magnesium and urinary excretion of potassium, calcium, magnesium and adenosine 3′:5′-cyclic monophosphate was studied in six healthy volunteers.
2. Serum levels of potassium, calcium, phosphate and magnesium decreased. Urinary excretion of potassium decreased, whereas those of calcium, magnesium and adenosine 3′:5′-cyclic monophosphate increased.
3. These results indicate that the hypocalcaemic and hypomagnesaemic effects of terbutaline can, at least partly, be explained by enhanced urinary excretion of calcium and magnesium. This may have important implications for the short-term terbutaline treatment of patients with, for example, cardiac disease.