Saline suppression testing-induced hypocalcemia and implications for clinical interpretations
Authors' conclusion
SST uniformly decreases serum calcium, which is likely to be due to the combination of variable dilution, increased renal clearance, and vitamin D status. These acute reductions in bioavailable calcium are associated with lower post-SST aldosterone. Given the critical role of extracellular calcium in regulating aldosterone production, these findings warrant renewed inquiry into the validity of SST interpretations for excluding primary aldosteronism.
Study context
- Population
- Prospectively recruited participants undergoing the saline suppression test (SST)
- Participants
- 86 participants
- Comparison
- Serum calcium before vs after SST
- Outcome
- Serum calcium during SST
Methodological detailsprospective
- Prospective
Main finding
As reported in the abstract
Participants with decreases in serum calcium
100%
Participants developing frank hypocalcemia
48%
Serum calcium, pre- to post-SST (mean ± SD), P < .001
2.30 ± 0.08 mmol/L to 2.13 ± 0.08 mmol/L
PTH, pre- to post-SST (mean ± SD), P < .001
6.06 ± 2.39 pmol/L to 8.13 ± 2.42 pmol/L
Further findings
Lower body surface area and serum calcium
- Association with greater reductions in serum calcium
- β = .33, P = .001
- Association with absolutely lower serum calcium
- β = .25, P = .001
Post-SST aldosterone <138 vs >277 pmol/L
- Aldosterone <138 pmol/L had lower post-SST calcium and 25(OH)D (P < .05) and higher post-SST PTH (P < .05) vs >277 pmol/L
Original publication
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