Biochemistry serum tests revealed increased creatinine (0.61 mg/dl) [estimated Glomerular Filtration Rate (eGFR): 56 ml/min/1.73 m2)], without associated electrolytes anomalies (potassium 5.3 mEq/L, chloride 106 mEq/L, total calcium 10.2 mg/dl, and phosphorus 4.9 mg/dl) except mild hypomagnesemia (magnesium 1.54 mg/dl) and elevated uric acid (7.4 mg/dl), and remarkably significant high intact parathyroid hormone (175 pg/ml), for the degree of renal function impairment, with adequate 25‐hydroxy‐vitamin D levels (25 ng/dl). This evidence concerns the gene PTH and familial primary hypomagnesemia.