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Endocrine Abstracts (2017) 49 GP51 | DOI: 10.1530/endoabs.49.GP51

ECE2017 Guided Posters Bone & Calcium Homeostasis 2 (9 abstracts)

Calcium to phosphorous ratio (Ca/P) as helpful index to recognize primary hyperparathyroidism, but not primary hypoparathyroidism: a big-data approach

Sara De Vincentis 1, , Daniele Santi 1, , Vincenzo Rochira 1, , Monica Setti 3 , Simonetta Tagliavini 4 , Manuela Varani 4 , Tommaso Trenti 4 , Manuela Simoni 1, & Bruno Madeo 1,


1Unit of Endocrinology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; 2Unit of Endocrinology, Department of Medicine, Endocrinology, Metabolism and Geriatrics, Azienda OU of Modena, Modena, Italy; 3Service of Clinical Engineering, Azienda USL of Modena, Modena, Italy; 4Department of Laboratory Medicine and Pathological Anatomy, Azienda USL of Modena, Modena, Italy.


Background: Primary hyperparathyroidism (HyperPT) and primary hypoparathyroidism (HypoPT) are often underdiagnosed. Several strategies have been investigated in the past in order to identify diagnostic parameters, although the diagnosis of both HyperPT and HypoPT remains challenging so far, especially in asymptomatic patients. Calcium (Ca) and phosphorus (P) are inversely related together, thus the Ca/P ratio could be an useful tool to define these conditions. Recently, we proposed for the first time a cut-off of 3.5 for Ca/P ratio for the diagnosis of HyperPT.

Aim: To evaluate the diagnostic value of the Ca/P ratio for HyperPT and HypoPT through a big-data approach.

Methodology: A retrospective, observational, case-control study on big-data was carried out. All examinations of parathyroid hormone (PTH), Ca and P performed at the laboratory of Modena Hospital from 2010 to 2016 were consecutively included. We considered only patients between 18 and 90 years of age. Laboratory ranges of normality for both PTH and Ca were used to divide records in HyperPT, HypoPT and controls.

Statistical analysis: The diagnostic accuracy of Ca/P ratio was investigated using receiver operator characteristics (ROC) curves in order to define cut-off points, which show higher sensitivity and specificity for the identification of affected patients.

Results: 46 597 records were considered. 576 HyperPT (1.2%), 323 HypoPT (0.7%) and 45 698 controls (98.1%) were found. Ca/P ratio was significantly different among groups (P<0.001). In particular, Ca/P ratio was significantly higher in HyperPT than controls (P<0.001). For the diagnosis of HyperPT, the threshold of 3.17 for Ca/P ratio was obtained by means of the ROC curve analysis, with 85% of both sensitivity and specificity. HypoPT showed lower Ca/P ratio compared to controls (P<0.001), although no useful threshold for the diagnosis was found at ROC curve because of the low sensitivity.

Conclusions: We confirm the high sensitivity and specificity of Ca/P ratio for the diagnosis of HyperPT using the largest cohort of patients available so far in the literature. On the contrary, Ca/P ratio does not contribute to identify patients with HypoPT and further researches are needed to better describe this condition. In conclusion, Ca/P ratio is a simple and inexpensive diagnostic tool to recognize HyperPT.

Volume 49

19th European Congress of Endocrinology

Lisbon, Portugal
20 May 2017 - 23 May 2017

European Society of Endocrinology 

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