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Validation of a blood gas device for ionized calcium analysis in Holstein cows
Abdülkerim Deniz1, Mert Metin2, Kemal Aksoy3
1Free Researcher for Clinical Biochemistry, İstanbul, Turkey.
Insights
The Edan i15 Vet device showed good accuracy for diagnosing subclinical hypocalcemia in dairy cows, though it cannot replace the Gem Premier 3000 analyzer. Serum total calcium measurements were less effective for diagnosis.
Area of Science:
- Veterinary Medicine
- Animal Health
- Dairy Cow Management
Background:
- Accurate ionized calcium (iCa) analysis is crucial for detecting hypocalcemia in dairy cows.
- The Edan i15 Vet (EDAN) device's performance for iCa in dairy cows requires validation.
Purpose of the Study:
- Validate the EDAN blood gas device against the Gem Premier 3000 (GEM) analyzer for iCa measurements.
- Evaluate the diagnostic capability of EDAN iCa and serum total calcium (TCa) for subclinical hypocalcemia.
Main Methods:
- Measured iCa using EDAN and GEM devices in 125 lactating Holstein cows (post-calving to day 27).
- Measured serum TCa using a wet biochemistry method.
- Analyzed agreement and diagnostic performance (sensitivity/specificity) using Bland-Altman and Passing-Bablok regressions.
Main Results:
- EDAN device showed a mean bias of 0.05 mmol/L against GEM.
- EDAN device achieved satisfactory sensitivity/specificity (e.g., 93%/94% at <1.00 mmol/L iCa cutoff) compared to GEM.
- Serum TCa measurements demonstrated lower sensitivity/specificity for diagnosing subclinical hypocalcemia compared to iCa.
Conclusions:
- The EDAN device is not interchangeable with GEM but has adequate diagnostic performance for subclinical hypocalcemia based on GEM-derived iCa cutoffs.
- Serum TCa cutoffs are not suitable for diagnosing subclinical hypocalcemia due to insufficient sensitivity/specificity.
- iCa values from both devices align with existing literature.
Background:
Accurate analysis of ionized calcium (iCa) is critical for the detection of hypocalcemia or subclinical hypocalcemia. The Edan i15 Vet (EDAN) blood gas device has not been validated for iCa in dairy cows.
Objectives:
We aimed to validate the EDAN blood gas device against the Gem Premier 3000 (GEM) analyzer by measuring iCa concentrations and evaluating the ability of these measurements, compared with serum total calcium (TCa) concentrations, to diagnose subclinical hypocalcemia.
Methods:
iCa concentrations were measured with the EDAN and GEM devices, and serum TCa concentrations were measured with a wet biochemistry method with blood from 125 lactating Holstein cows between calving to day 27 postpartum.
Results:
Bland-Altman plots showed a mean and total bias of 0.05 and 0.24 mmol/L for the EDAN device, respectively. The intercept did not include zero, but the slope included 1.0 in the Passing-Bablok regression. The sensitivity and specificity (Se/Sp) of the EDAN device were 93/94%, 93/90%, 91/93%, and 85/95% for iCa cut-off values of <1.00, 1.05, 1.10, and 1.15 mmol/L, respectively, as determined with the GEM device. The Se/Sp were 57/82% and 72/80% for EDAN and 57/80% and 72/79% for GEM at serum TCa cut-off points <2.15 and <2.00 mmol/L, respectively. The average iCa concentrations analyzed with the GEM and EDAN devices were 1.04 ± 0.18 and 1.09 ± 0.17, respectively.
Conclusions:
The EDAN device did not have satisfactory agreement with GEM and could not be used interchangeably, but it had satisfactory Se/Sp to diagnose subclinical hypocalcemia compared with the GEM-derived iCa cut-off points. Serum TCa concentration cut-off values were not suitable for diagnosing subclinical hypocalcemia because of unsatisfactory Se/Sp compared with iCa concentrations analyzed by the GEM and EDAN devices. The iCa values analyzed using the EDAN and GEM devices were consistent with previously reported data.
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