Serum Calcium to Phosphorous (Ca/P) Ratio in the Diagnosis of Ca-P Metabolism Disorders: a Multicentre Study

The aim of this study is to investigate the accuracy and diagnostic value of Ca/P ratio in the diagnosis of primary hyperparathyroidism and hypoparathyroidism. The definition of a valid cut-off of serum Ca/P ratio for patients with these disorders will be of help especially in those patients with apparently normal biochemical profile, but suggestive for primary hyperparathyroidism and hypoparathyroidism.

Inclusion criteria

• patients with diagnosis of primary hyperparathyroidism
• patients with diagnosis of hypoparathyroidism
• subjects with normal Calcium-Phosphorus metabolism

Exclusion criteria

for both cases and controls will be:

• age younger than 18 or older than 90 years
• severe renal and liver diseases (i.e. glomerular filtration rate (GFR) <30 ml/min)
• hyperparathyroidism secondary to Vitamin D deficiency
• active metabolic bone disease (e.g. Paget's disease of the bone, osteomalacia, rickets, etc)
• any type of cancer
• malnutrition
• severe obesity (BMI > 40 kg/m2)
• a history of gastrointestinal malabsorption
• sarcoidosis
• hypercortisolism
• diabetes insipidus
• hyperthyroidism
• pseudohypoparathyroidism
• familial hypocalciuric hypercalcemia (FHH)
• treatment with steroids, active forms of vitamin D (calcitriol, ergocalciferol, etc), thiazides, phosphate binders, lithium, cinacalcet, bisphosphonates, and denosumab.