Serum Calcium to Phosphorous (Ca/P) Ratio in the Diagnosis of Ca-P Metabolism Disorders: a Multicentre Study
Serum Calcium to Phosphorous (Ca/P) Ratio in the Diagnosis of Ca-P Metabolism Disorders: a Multicentre Study
Primary hyperparathyroidism (PHPT) and Hypoparathyroidism (HP) are two of the most frequent
 disorder of Calcium-Phosphorus (Ca-P) metabolism. The Ca/P ratio is an accurate tool to
 differentiate patients with PHPT from healthy subjects, according to a previous single-centre
 study. The reliability of this index is based on the fact that serum Ca and P are inversely
 related together either in healthy subjects or in patients with PHPT and HP.
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.