Renin: activity, reactivity and concentration in a population survey. Relationship to blood pressure

Relative significance of plasma renin activity and concentration in physiologic and pathophysiologic conditions

Plasma renin activity (PRA) and concentration, measured after acid treatment of the plasma (PRC3.3), were determined on the same plasma samples in different conditions. Log PRA and log PRC3.3 were significantly (P less than 0.001) and similarly related to sodium intake, age, and plasma aldosterone concentration in normal subjects. The correlation coefficient between log PRA and log PRC3.3 was 0.49 in 80 sodium-replete and sodium-deplete normal subjects, and it was 0.84 in 84 hypertensive patients untreated or under treatment with thiazides. On the contrary, during beta adrenergic blockade, PRA decreased significantly (P less than 0.001) by 62% while the changes in PRC3.3 were not significant. At maximal exercise, PRA increased significantly by 168% while the PRC3.3 increase of 24% was not significant. In hypertensive patients with unilateral renal artery stenosis the ipsilateral renal vein/artery ratio was higher for PRA (2.46) than for PRC3.3 (1.56), whereas both ratios on the controlateral side were similar and close to one (1.14 and 1.06). The conditions in which PRA and PRC3.3 determinations are concordant or discordant are discussed.

Impact of new diagnostic methods on the differential diagnosis and treatment of secondary amenorrhoea

The development of homologous prolactin assays, multiple pituitary stimulation, tomography, and computerised axial tomography permit more detailed investigation of patients with secondary amenorrhoea than was formerly possible. 39% of 90 patients with secondary amenorrhoea had hyperprolactinaemia. 10 patients (11% of total) had pituitary tumours. 8 of these women had galactorrhoea (27% of those with galactorrhoea). For patients with hyperprolactinaemia but no tumour, bromocriptine is the treatment of first choice rather than clomiphene or human gonadotrophins. The best treatment for patients with detectable tumour is controversial, particularly when the tumour is confined to the sella turcica. Whether or not these tumors are true neoplasms remains to be determined. Clinically, a history of secondary anemorrhoea with or without galactorrhoea following withdrawal of oral contraceptives remains the commonest presenting syndrome.