Biochemical Ratios for Predicting Primary Hyperparathyroidism: Revisiting Simple yet Powerful Diagnostic Tools
Authors' conclusion
The Ca × Cl/P and Ca/P ratios demonstrate substantial diagnostic value for PHPT, while biochemical markers exhibited limited specificity in NPHPT. These findings highlight their role in screening but emphasize the need for additional diagnostic approaches.
Study context
- Population
- Participants with primary hyperparathyroidism (PHPT), NPHPT, VDSHPT and controls
- Participants
- 437 participants
- Exposure
- PHPT vs NPHPT vs VDSHPT vs controls; diagnostic performance of biochemical ratios for PHPT
- PHPTn = 161
- NPHPTn = 97
- VDSHPTn = 89
- Controln = 90reference
- Outcome
- Utility of biochemical markers (serum Ca, phosphate, chloride, PTH, vitamin D; Ca/P, Cl/P, Ca × Cl/P, PF Index [Ca × PTH/P]) in distinguishing PHPT, NPHPT and VDSHPT
Main finding
As reported in the abstract
Diagnostic accuracy for PHPT
| Group | AUC | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|
| Ca × Cl/P ratio | — not stated in the abstract | — not stated in the abstract | 89.2% | 82.2% | — not stated in the abstract |
| Ca/P ratio | — not stated in the abstract | 77.6% | — not stated in the abstract | — not stated in the abstract | 86.6% |
| PF Index | 0.851 (95% CI 0.816-0.886) | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract |
| Cl/P ratio | 0.766 (95% CI 0.711-0.820) | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract |
AUC
Ca × Cl/P ratio— not stated in the abstract
Ca/P ratio— not stated in the abstract
PF Index0.851 (95% CI 0.816-0.886)
Cl/P ratio0.766 (95% CI 0.711-0.820)
Sensitivity
Ca × Cl/P ratio— not stated in the abstract
Ca/P ratio77.6%
PF Index— not stated in the abstract
Cl/P ratio— not stated in the abstract
Specificity
Ca × Cl/P ratio89.2%
Ca/P ratio— not stated in the abstract
PF Index— not stated in the abstract
Cl/P ratio— not stated in the abstract
PPV
Ca × Cl/P ratio82.2%
Ca/P ratio— not stated in the abstract
PF Index— not stated in the abstract
Cl/P ratio— not stated in the abstract
NPV
Ca × Cl/P ratio— not stated in the abstract
Ca/P ratio86.6%
PF Index— not stated in the abstract
Cl/P ratio— not stated in the abstract
— not stated in the abstract
Observational data: associations, not effects.
Further findings
| Outcome | PHPT | P value |
|---|---|---|
| Serum Ca | mean 2.73 ± 0.17 mmol/L | |
| Serum phosphate | mean 0.70 ± 0.19 mmol/L | |
| Ca/P ratioBetween NPHPT and VDSHPT · no significant difference | mean 4.17 ± 1.21 | P = 0.63 |
| Ca × Cl/P ratioBetween NPHPT and VDSHPT · no significant difference | mean 448.5 ± 133.6 | P = 0.74 |
- Serum Ca — Ca highest in PHPT
- p < 0.001
- Serum phosphate — Phosphate lowest in PHPT
- p < 0.001
- Ca/P ratio — Ca/P ratio significantly higher in PHPT
- p < 0.001
- Ca × Cl/P ratio — Ca × Cl/P ratio significantly higher in PHPT
- p < 0.001
PTH
- PTH significantly elevated in PHPT, NPHPT and VDSHPT vs controls
- P < 0.001
Diagnostic performance in NPHPT
- All markers had high sensitivity but poor specificity
- 1.6%-23.2%
Original publication
Biochemical Ratios for Predicting Primary Hyperparathyroidism: Revisiting Simple yet Powerful Diagnostic Tools. Clin Endocrinol (Oxf). Published 24 October 2025. doi:10.
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