Reliability of Serum Calcium to Phosphorus (Ca/P) Ratio as an Accurate and Inexpensive Tool to Define Disorders of Ca-P Metabolism

Serum Calcium to Phosphorus (Ca/P) Ratio to Define Disorders of Ca-P Metabolism

BACKGROUND: Primary hyperparathyroidism (PHPT) is the third most common endocrine disorder. The Ca/P ratio is an accurate tool to differentiate patients with PHPT (>3.5 if Ca and P are expressed in mg/dl) from healthy subjects. The reliability of this index is based on the fact that serum Ca and P are inversely related together. However, other disorders of the Ca-P metabolism, such as hypophosphoremia (HypoP) not related to PHPT, might also impair the Ca/P ratio.

OBJECTIVE: To validate the accuracy of Ca/P ratio in the diagnosis of Ca-P metabolism disorders, including also patients with documented HypoP not related to PHPT.

METHODS: A single-center, retrospective, case-control study will be carried out.

Biochemical measurements will include parathormone (PTH), vitamin D, serum Ca and P, serum albumin and creatinine.

Study Overview

• Status: Completed
• Conditions: Phosphorus and Calcium Disorders
• Intervention / Treatment: Other: No intervention are provided

• Study Type: Observational
• Enrollment (Actual): 606

Contacts and Locations

Study Locations

• Italy
  • Modena, Italy, 41124
    • Azienda Ospedaliero - Universitaria di Modena

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 90 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: N/A
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Serum Calcium to Phosphorus ratio will be compared among patients with different disorders of calcium-phosphorus metabolism (primary hyperparathyroidism and hypophosphoremia) and controls.

Description

Inclusion Criteria:

• patients with diagnosis of primary hyperparathyroidism
• HIV-infected patients with reduced phosphorus but normal calcium
• 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.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
First study group: patients with PHPT; Patients aged between 18-90 years old with primary hyperparathyroidism who had been diagnosed in the Unit of Endocrinology of the University of Modena and Reggio Emilia. 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.	Other: No intervention are provided
Second study group: patients with HypoP; Subjects with reduced serum P, but normal serum Ca, will be enrolled among HIV-infected patients on HAART treatment from the Modena cohort. 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.	Other: No intervention are provided
Control group; Patients that underwent biochemical examination by primary care physician or by endocrinologist in order to assess their calcium-phosphorus metabolism state with normal results. 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.	Other: No intervention are provided

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Serum Calcium to Phosphorus ratio	Calculated formula (serum calcium to serum phosphorus ratio)	Assessed only once at the diagnosis (from January 2005 to January 2018)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Serum Calcium	From blood sample - Unit of measurement: mg/dl	Assessed only once at the diagnosis (from January 2005 to January 2018)
Serum Phosphorus	From blood sample - Unit of measurement: mg/dl	Assessed only once at the diagnosis (from January 2005 to January 2018)
Serum Parathormone	From blood sample - Unit of measurement: pg/ml	Assessed only once at the diagnosis (from January 2005 to January 2018)

Collaborators and Investigators

• Sponsor: Azienda Ospedaliero-Universitaria di Modena

Study record dates

Study Major Dates

• Study Start (ACTUAL): January 1, 2011
• Primary Completion (ACTUAL): January 1, 2018
• Study Completion (ACTUAL): January 1, 2018

Study Registration Dates

• First Submitted: July 10, 2018
• First Submitted That Met QC Criteria: July 19, 2018
• First Posted (ACTUAL): July 27, 2018

Study Record Updates

• Last Update Posted (ACTUAL): July 27, 2018
• Last Update Submitted That Met QC Criteria: July 19, 2018
• Last Verified: July 1, 2018

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Disease
• Other Study ID Numbers: 0032443/15

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No