Parathyroid hormone and anaemia--an erythrocyte osmotic fragility study in primary and secondary hyperparathyroidism.

Parathyroid hormone (PTH) has been shown in vitro to enhance erythrocyte osmotic fragility (EOF) and has been incriminated as a factor in the anaemia seen in patients with primary hyperparathyroidism and in patients with renal disease and secondary hyperparathyroidism. Enhanced EOF has also been shown in patients with chronic renal failure but did not correlate with PTH levels. We studied a group of patients with primary hyperparathyroidism with and without anaemia, and patients with secondary hyperparathyroidism and anaemia. We found that EOF studies in these patients did not differ from normal control groups and that there was no relation between PTH, EOF, and haematocrit in either study group. We conclude that PTH over a range of concentrations seen in vivo does not affect erythrocyte osmotic fragility or cause anaemia.