Beta-2 microglobulinuria and long-term outcome following curative surgery for primary hyperparathyroidism

Twentyseven patients admitted for surgery for primary hyperparathyroidism were studied preoperatively. Fifteen were normotensive and 12 were either hypertensive, diastolic blood pressure > 95 mmHg or had a raised serum creatinine measuring 109.7 (55-171) mumol/l. The beta 2 microglobulin (beta 2M) urinary excretion was measured on all patients. The beta 2M levels were raised in all patients preoperatively even in those patients who had normal values for conventional renal function tests. Following curative surgery the values are returned to the normal range. The patients were followed up for a mean of 4.2 (2.8-5.6) years. Six patients who were initially normotensive subsequently developed hypertension and the initial beta 2M ratio was significantly higher 386 (122-680) micrograms/l compared to those who remained normotensive 186 (95-340) micrograms/l (p < 0.05). Even higher preoperative beta 2M excretion was found in the initial hypertensive group 505 (87-1160) micrograms/l compared to those who later developed hypertension 386 (122-680) micrograms/l, p < 0.001. This preliminary study suggests that preoperative beta 2M urinary excretion may be of value in identifying those patients who will subsequently develop hypertension, an identified long term cause of death in patients operated on for primary hyperparathyroidism. Further studies are indicated.