Endocrine Abstracts

Introduction: Hypoparathyroidism (HP) is characterized by low serum calcium and increased phosphate levels associated with inappropriately low serum PTH levels. Clinical manifestations of HP are tingling, muscle cramps, seizures, nephrocalcinosis, kidney stone, kidney failure, depression and anxiety.

Objective: Quantify the chronic symptoms and complications of HP in our monocentric cohort.

Material and methods: We conducted a retrospective study involving patients that attended the Endocrinology Unit of S.Orsola-Malpighi Hospital in Bologna from 1980 to 2016. HP was confirmed by hypocalcemia with a simultaneous low or inappropriately normal PTH level for at least 1 yr. We evaluated serum and urine laboratory results in association with clinical manifestation.

Results: We identified 130 permanently hypoparathyroid patients. Mean age at the end of the observation period was 61±16 (range 21–94) yr, and the cohort was 83% female. The main cause of HP was neck surgery. 90.8% of patients were treated with calcium supplements (mostly carbonate) and/or calcitriol. In addition, 14.6% took thiazide diuretics and 7.7% phosphate binders. Mean serum calcium was 8.4±0.8 mg/dl. Time-weighted average for calcium was between 7.5 and 9.5 mg/dl for 80.8% of patients, while 12.3% was under this target and 6.9% over the target. The average calcium-phosphate product was 38.3±6.9 mg²/dl², and 98.4% had a calcium-phosphate product under 55 mg²/dl². Hypercalciuria was recorded in 27.7% of the cohort. Calcium urinary levels were correlated with age (P=0.009), serum calcium levels (P=0.001) and calcitriol dose (P=0.005). As expected, neuromuscular symptoms were inversely correlated with serum calcium levels, and only 8% of patients with calcium levels under 9 mg/dl was symptomatic. Nevertheless, 50% of patients were asymptomatic with calcium levels under 6.5 mg/dl. Symptomatic hypocalcemia and vitamin D intoxication required hospitalization in 6 and 11 occasions, respectively. Chronic kidney disease (CKD) was observed in 27.7% of the cohort. Thirty patients developed moderate CKD and six severe CKD. By multivariate Cox regression, eGFR was inversely associated with serum calcium levels (P=0.04; HR 1.7 CI 95% 1.0–2.9). Nephrolitiasis was detected in 14.6% and nephrocalcinosis in 2.3% of the cohort. Soft tissue calcifications were observed in 14.6% of the cohort. Bone fractures occurrred in 15.3% (20/130) of patients, while 19.3% (12/62) had a densitometric diagnosis of osteoporosis. In addition, hospitalization for cardiovascular events (20.8%), malignancy (10%), and infections (7.7%) were recorded.

Conclusions: Hyoparathyroidism and its treatment are associated with a high rate of complications, particularly kidney disease.