Key result
Hyperthyroidism is linked to elevated active plasma renin activity that propranolol administration reduces.
Why the study?
The relationship between active and inactive plasma renin activity in patients with hyperthyroidism and the effect of treatment or propranolol was unclear.
Does hyperthyroidism and its treatment with propranolol affect active and inactive plasma renin activity?
Observational (n=36)
Does hyperthyroidism and its treatment with propranolol affect active and inactive plasma renin activity?
In hyperthyroidism, increased sympathetic activity likely facilitates the in vivo conversion of inactive renin to active renin, a process that can be attenuated by propranolol.
Answers are grounded in this paper and cite their sources.
Hyperthyroidism-associated renin elevation may reflect sympathetic drive; leaves open whether propranolol alters clinical outcomes in this setting.
Active and inactive PRA were measured after 1 h at rest in 16 normal controls and 20 patients with hyperthyroidism. In some of the patients these measurements were repeated after they had become euthyroid or received 90 mg propranolol for 1 week. Inactive PRA was determined as the difference between total PRA after trypsin activation and active PRA. Active PRA was significantly higher (P less than 0.01) in untreated patients than in normal subjects; however, the inactive PRA of patients was not different compared with that of normal subjects. Active PRA was normalized, and inactive PRA did not change after achievement of euthyroidism. The proportion of active of total PRA was significantly correlated with the levels of serum thyroid hormones (T3 and T4) in hyperthyroid patients (r = 0.46; P less than 0.05 and r = 0.55; P less than 0.01, respectively). The administration of propranolol reduced active PRA (P less than 0.05) and increased inactive PRA slightly but not significantly. These results indicate that in hyperthyroidism, the in vivo conversion of inactive renin to active renin is probably facilitated by increased sympathetic activity.
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Nakamaru et al. (1983) conducted an observational in Hyperthyroidism (n=36). Hyperthyroidism vs. Normal controls was evaluated on Active plasma renin activity (PRA) (p=<0.01). Hyperthyroidism was associated with higher active plasma renin activity compared to normal controls, which was reduced by propranolol administration.
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