This calculator applies an albumin adjustment to a measured total serum magnesium result. Some circulating magnesium is protein-bound, so a low albumin concentration can lower total magnesium without describing the ionized fraction directly. The displayed number is an estimate from one proposed correction equation, not a replacement for laboratory interpretation.
The page converts magnesium to mg/dL and albumin to g/dL, then uses measured magnesium + 0.1 × (4 − albumin). Published correction approaches are not universal, and laboratory methods and reference intervals differ. Review the original report, symptoms, kidney function, medicines, and clinical setting with a qualified professional.
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How to Use This Calculator
Enter a positive measured magnesium value and select mg/dL, mmol/L, or mEq/L exactly as printed on the report.
Enter a positive albumin value and select g/dL or g/L.
Select Calculate. For the computation, the page multiplies mmol/L magnesium by 2.43, multiplies mEq/L by 1.215, and divides g/L albumin by 10.
It applies the albumin adjustment, rounds to two decimal places, and displays mg/dL.
The accompanying Below, Within, or Above label uses fixed 1.7 and 2.4 mg/dL cutoffs written into the page and explicitly calls them this calculator’s reference band. They are not universal laboratory intervals; the reporting laboratory’s interval and the patient’s context take priority.
Page conversions: magnesium in mmol/L × 2.43 = mg/dL; magnesium in mEq/L × 1.215 = mg/dL; albumin in g/L × 0.1 = g/dL.
The conversion factors reflect magnesium’s molar mass and divalent charge. The albumin coefficient is an empirical convention rather than a physical conversion. Other publications express adjustments in mmol/L or mEq/L with different coefficients, so equations must not be mixed across units.
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Variables Explained
Input or output
Meaning
Measured magnesium
Total serum magnesium from the laboratory report, with its original unit.
Albumin
Serum albumin concentration measured near the same time, entered in g/dL or g/L.
4.0 g/dL
Reference albumin built into this particular equation.
0.1
Adjustment added in mg/dL for each 1 g/dL that albumin is below 4.0; it is equation-specific.
Adjusted result
An estimated total-magnesium value in mg/dL, rounded to two decimals.
Status
A page label based on fixed cutoffs, not a diagnosis or universal laboratory range.
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Worked Example
Take measured magnesium of 1.6 mg/dL and albumin of 2.0 g/dL. The albumin difference is 4.0 − 2.0 = 2.0 g/dL. Multiply by 0.1 to obtain 0.2 mg/dL, then add it to the measured magnesium: 1.6 + 0.2 = 1.8 mg/dL. The page displays 1.8 mg/dL and labels it Within this calculator's reference band.
For a unit-conversion check, 0.658 mmol/L magnesium becomes about 0.658 × 2.43 = 1.599 mg/dL. Albumin 20 g/L becomes 2.0 g/dL. The adjusted value is again about 1.80 mg/dL after rounding. Small differences can arise from conversion-factor precision and laboratory rounding.
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Why Use This Calculator?
Read the output as the result of the stated equation, not as a measured ionized-magnesium concentration. A correction may help explain why total magnesium looks low when albumin is low, but it cannot determine the cause or severity of a magnesium disorder. A value inside this page’s band also does not rule out a clinically important problem.
Albumin above 4 g/dL makes the formula subtract from measured magnesium. Whether that is appropriate in a particular case should be judged by the laboratory or clinician. Total and ionized magnesium are different measurements, and results can be influenced by sampling, kidney function, gastrointestinal loss, medicines, acid-base state, and acute illness.
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Common Mistakes
Selecting mg/dL for a mmol/L result, which changes the scale substantially.
Entering 20 for albumin while selecting g/dL when the report actually says 20 g/L.
Ignoring the mg/dL unit displayed with the adjusted result.
Treating the fixed reference band as universal. Use the interval printed by the performing laboratory.
Using an albumin result from a different clinical episode without checking whether it is comparable.
Confusing estimated adjusted total magnesium with directly measured ionized magnesium.
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Frequently Asked Questions
Is corrected magnesium the same as ionized magnesium?
No. This result estimates an albumin-adjusted total concentration. Ionized magnesium is a separately measured fraction. Do not substitute the calculated value for a laboratory ionized-magnesium measurement.
What unit does the result use?
The calculator converts the input and calculates the final number in mg/dL. The result box displays that unit, and the page’s reference band also uses the mg/dL scale.
Why might my laboratory classify the result differently?
Laboratories can use different instruments, populations, and reference intervals. This page uses fixed cutoffs of 1.7 and 2.4 mg/dL, so its label may not match the interval printed on your report.
Can this calculator diagnose magnesium deficiency?
No. It only applies one numerical adjustment. Diagnosis and treatment require the measured results and wider clinical information to be reviewed by a qualified healthcare professional.
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