Endocrine Abstracts

Diagnostic value of daily calciuria on a strict diet in patients with primary hyperparathyroidism. The most common cause of primary hyperparathyroidism is monoclonal hyperplasia of a single mutant cell. Most somatic mutations found in adenomas regulate the cell cycle by increasing the speed of cell division. This means that stimulating stimuli, such as negative calcium balance, increased phosphorus retention, disturbances of the calcitriol/VDR/FGF23/KLOTHO axis, or lack of inhibitory stimuli, such as estrogen deficiency, will favor the development of adenomas. One of the causes of stimulation of parathyroid cell division is chronic renal calcium loss. The aim of the study was to assess daily calciuria in a population of patients with hyperparathyroidism hospitalized at the Department of Endocrinology of the Medical University of Warsaw. Due to the predominant hyperabsorptive nature of hypercalciuria, two daily urine collections were performed in the studied patients on a standard diet and on a strict diet. The results were correlated with the assessment of the urinary system for nephrolithiasis and the level of vitamin D. The results showed significant differences in calcium excretion on a regular and strict diet in some patients, which was interpreted as the possibility of co-occurring mild tubulopathies. A negative calcium balance would promote increased proliferation of a clone of parathyroid cells whose cell cycle is disrupted by the presence of the somatic mutation.

Conclusion: Assessment of fasting 24-hour calciuria as an adjunct to routine 24-hour calciuria testing may help determine the cause of stimulation of a clone of cells with a somatic mutation predisposing to hyperparathyroidism