Related Experiment Videos
Calcium in patients on hemodialysis
T Ring1, P Halkier, H H Hansen
1Medical Department C, Aalborg Hospital, Denmark.
Insights
For hemodialysis patients, 50% of total calcium approximates ionized calcium. However, albumin and phosphate levels also impact ionized calcium, making standard correction formulas less reliable.
Area of Science:
- Nephrology
- Clinical Chemistry
- Biochemistry
Background:
- Accurate measurement of ionized calcium is crucial for managing patients undergoing chronic maintenance hemodialysis.
- Conventional methods for correcting total calcium to estimate ionized calcium may be inaccurate in this patient population.
Purpose of the Study:
- To evaluate the reliability of using 50% of total calcium as an approximation for ionized calcium in hemodialysis patients.
- To assess the influence of albumin and phosphate on ionized calcium levels in this cohort.
- To determine the efficacy of conventional albumin correction formulas in hemodialysis patients.
Main Methods:
- Analysis of 415 measurements from 33 patients on chronic maintenance hemodialysis.
- Comparison of total calcium percentages with measured ionized calcium levels.
- Evaluation of the impact of albumin and phosphate concentrations.
Main Results:
- Fifty percent of total calcium provided a valuable approximation for ionized calcium within specific ranges (1.59–3.33 mmol/l for total calcium, 0.79–1.62 mmol/l for ionized calcium).
- A small but significant effect of albumin and phosphate on ionized calcium was observed.
- Conventional albumin correction formulas demonstrated poor value for estimating ionized calcium in these patients.
Conclusions:
- While 50% of total calcium is a useful initial estimate, it does not fully account for variations in ionized calcium in hemodialysis patients.
- Albumin and phosphate levels significantly affect ionized calcium, necessitating alternative or refined correction methods.
- Standard albumin correction formulas are inadequate for accurately assessing ionized calcium in patients undergoing maintenance hemodialysis.
Abstract:
Analyzing 415 measurements from 33 patients on chronic maintenance hemodialysis we confirm that 50% of total calcium in the range 1.59 to 3.33 mmol/l gives a valuable approximation to ionized calcium in the range 0.79 to 1.62 mmol/l. However, a small but significant effect of albumin and phosphate on ionized calcium can also be demonstrated. Conventional albumin correction of total calcium using the formula: total calcium + (43 g/l-Albumin g/l).0.017 mmol/g is of poor value in these patients on maintenance hemodialysis.