Diagnostic performance of the calcium/phosphate ratio for primary hyperparathyroidism in southwest China

Abstract

Background: The diagnosis of primary hyperparathyroidism (PHPT) remains a challenge because of increased asymptomatic PHPT or patients with normocalcaemic PHPT (NPHPT). In addition, some primary hospitals in China have no equipment to measure PTH levels. Therefore, an additional, simple, and inexpensive laboratory biochemical marker is urgently needed. The calcium/phosphate (Ca/P) ratio and chloride/phosphate (Cl/P) ratio have been proposed as suitable tools to diagnose PHPT in Europe; however, the Ca/P ratio has never been tested in China. We aimed to conduct a confirmatory study to explore the diagnostic performance of the Ca/P ratio for PHPT in China. Methods: From January 2015 to December 2020, a total of 155 patients who underwent parathyroidectomy (143 PHPT patients and 12 NPHPT patients) and 153 controls were enrolled in this single-center, retrospective study. Serum calcium, phosphate, parathyroid hormone, 25-OH vitamin D, chloride, ALT, AST, eGFR, and creatinine levels were recorded for all the study participants. Pairwise comparisons were made between groups, and the diagnostic performance of the Ca/P ratio was determined using receiver operating characteristic (ROC) analysis. Results: Patients with PHPT had a higher Ca/P ratio than controls (P < 0.001). A Ca/P ratio above 2.94 with a sensitivity of 95.5% and specificity of 98.7% can distinguish PHPT patients from healthy individuals. This index was positively correlated with the PTH level (r = 0.875, P < 0.001). Conclusion: The Ca/P ratio is an ideal and inexpensive indicator for diagnosing PHPT in China when using a cutoff value of 2.94.

Serum Calcium/Phosphorus Ratio in Biochemical Screening of Primary Hyperparathyroidism

“…When this ratio was evaluated in 35 patients with NPHPT, the sensitivity decreased to 71%, while the specificity of 88% was maintained. A recent study in the Chinese population confirmed that a Ca/P ratio of over 2.94 can distinguish PHPT patients from healthy controls with a sensitivity of 95.5% and a specificity of 98.7% 11 . In this study, we aimed to investigate the diagnostic value of serum Ca/P ratio in PHPT screening in our patient population with PHPT.…”

“…In another study by Madeo et al 15 involving 142 patients diagnosed with NPHPT, the Ca/P ratio cutoff value of 2.55 showed high sensitivity (71.1%) and specificity (87.9%). Yin et al 11 recently reported a sensitivity of 95.5% and specificity of 98.7% with a Ca/P ratio cutoff value of 2.94, and this index was positively correlated with the PTH level (r=0.875, p<0.001). In another study, the cutoff value of 2.55 for the Ca/P ratio served as a reliable predictor for the diagnosis of PHPT with 95.6% sensitivity and 63.6% specificity 16 .…”

Application of calcium-to-phosphorus (Ca/P) ratio in the diagnosis of pseudohypoparathyroidism: another piece in the puzzle of diagnosis of Ca-P metabolism disorders

“…The serum calcium (Ca)–to–phosphorous (P) (Ca/P) ratio has been proposed as a simple tool to detect disorders of Ca and P metabolism such as primary hyperparathyroidism (PHPT) and chronic hypoparathyroidism (HPT) ( 1 – 4 ). In detail, it has been demonstrated that the serum Ca/P ratio is highly accurate in detecting PHPT when above 2.55 (3.3 if serum Ca and P are expressed in mg/dL) and HPT when below 1.78 (2.32 if serum Ca and P are expressed in mg/dL) ( 3 ).…”