The clinical significance of calcium/magnesium ratio in primary hyperparathyroidism: unveiling a clinical association.

Purpose: In previous studies, magnesium (Mg) was found to be lower in cases with more severe primary hyperparathyroidism (PHPT) and higher calcium (Ca) levels. This study evaluated the relationship between serum Mg and serum Ca and phosphorus (P) levels in PHPT and their utility in determining the presence of osteoporosis and nephrolithiasis.

Methods: Patients who were followed up with PHPT between March 2019 and March 2023 were analyzed retrospectively. Biochemical data, renal ultrasonography results, dual-energy x-ray absorptiometry (DEXA) reports, and technetium 99 m sestamibi parathyroid scintigraphy reports were obtained. MgxP, Mg/P, Ca/P, and corrected Ca (cCa)/P values were calculated. The relationships between biochemical parameters and clinical outcomes were evaluated statistically.

Results: A total of 543 patients were included in the study. Patients with nephrolithiasis had higher cCa/Mg or Ca/Mg than those without nephrolithiasis. Additionally, ROC analysis revealed that cCa/Mg greater than 5.24 could identify the presence of nephrolithiasis with a sensitivity of 73.3% and a specificity of 73%. No statistically significant correlation existed between the results of the Mg/P, MgxP, cCa/Mg, Ca/Mg values, and DEXA-bone mineral densitometry(BMD).

Conclusion: Ca/Mg and cCa/Mg ratios in particular seem more valuable in determining the presence of nephrolithiasis than the currently used 24-h urine Ca measurement. Compared to urinary Ca measurements, they are cheaper, more practical, and more accessible.