Comparison of Normocalcemic vs Hypercalcemic Primary Hyperparathyroidism in a Hypercalciuric Renal Stone Population
Authors' conclusion
Our data show the relevance of dynamic tests to unmask NHPT in patients with hypercalciuric renal stones.
Study context
- Population
- Patients with hypercalciuric renal stones and a final diagnosis of primary hyperparathyroidism (PHPT) (postload ionized calcium > 1.31 mmol/L and PTH > 30 pg/mL)of 1671 with hypercalciuria
- Participants
- 91 patients
- Exposure
- Normocalcemic PHPT vs hypercalcemic PHPT
- NHPTn = 35
- Hypercalcemic hyperparathyroidism (HPHPT)n = 56reference
- Outcome
- Prevalence of NHPT among PHPT
Methodological detailsroutine calcium load test, calcium-restricted diet
- Routine calcium load test
- Calcium-restricted diet
Main finding
As reported in the abstract
Prevalence of NHPT, of all PHPT
40%
Misclassified by total serum calcium, NHPT
4 of 35
Misclassified by total serum calcium, HPHPT
7 of 56
Observational data: associations, not effects.
Further findings
| Outcome | NHPT | HPHPT | P value |
|---|---|---|---|
| Renal calcium excretion increase postload · after calcium load | 303% | 176% | P = 0.01 |
| Parathyroidectomy | 18 events | 40 events |
- Renal calcium excretion increase postload — Likely explained by a lesser PTH decrease in HPHPT
- P = .02
Ionized calcium, calcium diet, 24-h calciuria, calcitriol, parathyroid weight, stone composition, bone remodeling biomarkers
- iCa higher in HPHPT fasting and after calcium load
- No difference for calcium diet, 24-h calciuria or calcitriol
- No significant differences in parathyroid weight, stone composition or bone remodeling biomarkers
Association between pooled preload and postload iCa and PTH
- Strong negative association only in NHPT
- P < 0.0001
Original publication
Comparison of Normocalcemic vs Hypercalcemic Primary Hyperparathyroidism in a Hypercalciuric Renal Stone Population. J Clin Endocrinol Metab. Published 18 March 2024. doi:10.
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