Secondary causes of hyperparathyroidism need to be excluded, such as medications known to affect PTH levels (diuretics, lithium, denosumab, bisphosphonates, anticonvulsants, and phosphorus), reduced serum vitamin D levels, chronic kidney disease (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2), renal calcium loss (hypercalciuria), and diseases of the gastrointestinal tract that interfere with calcium absorption (celiac disease, inflammatory bowel disease, and bariatric surgery) [3–6]. The gene discussed is PTH; the disease is Hypercalciuria.