Renal function in 711 patients with hypoparathyroidism during more than 4 years of therapy

Patients (pts) with hypoparathyroidism (HypoPT) are at risk to develop renal failure possibly caused by hypercalciuria and nephrocalcinosis. We retrospectively evaluated the data of 711 Patients with HypoPT in 3 endocrine centres in Germany. Methods: Records of 711 pts with HypoPT were reviewed. Patients were predominantly female (n=592, male: n=119; age 50.9±14.1 years, range 12 – 99 years). The following parameters were documented during treatment and follow-up (MW 52±40.9 months, time range 2–334 months): medication, calcium in serum and urine, phosphate, calcium-phosphate-product (CPP), glomerular filtration rate (GFR) calculated by CKD-EPI formula. Results: Of these 711 pts. 29 had idiopathic HypoPT, 10 HypoPT after parathyroidectomy, 669 after thyroid operation. At first visit 4.0% of pts <40 years, 11.1% in the age group 40–59, 28.4% in the age group 60–69, and 49.0% in pts >69 years had a GFR < 60 ml/min. At the last visit no worsening of renal function was observed (GFR < 60 ml/min in 5.9% <40 years, 9.8% in the age group 40–59, 17.1% in the age group 60–69, 36.0% >69 years). An elevated CPP > 55 mg2/dl2 was found in 25 pts (3.5%). In these pts the proportion of GFR < 60 ml/min was 33.5% compared to 21.1% of those with normal CPP. In comparison of the therapeutic strategies pts treated exclusively with dihydrotachysterol renal function was the lowest (n=46; mean GFR 70.2±26.2 ml/min). In pts treated with calcitriol and calcium (n=226) mean GFR was better than in all other treatment groups (84.9±20.9). Conclusion: We saw no worsening of renal function in a large cohort of patients with HypoPT during 4 years of therapy. High CPP was associated with lower GFR. Different treatment strategies of HypoPT seem to affect kidney function.