Serum reference intervals of micronutrients, vitamins, and interleukins among healthy adults in South-Western Nigeria

Objectives

Clinical decision making depends mostly on appropriate application of numerical pathology reports from laboratory results, interpreted by comparison with reference intervals. We determined serum reference intervals of micronutrients, vitamins, and detectable interleukins among healthy adults in South-Western Nigeria.

Design and methods

This prospective study used a priori selection approach in blood-donors. They were screened for conditions that could elicit cytokine production.

Serum micronutrients were assayed using Atomic Absorption Spectrophotometry; interleukins and vitamins by high Performance Liquid Chromatography. The reference intervals (RIs) were estimated at 2.5th percentile and 97.5th percentile.

Results

One hundred and eighteen (118) apparently healthy subjects, aged 18–56 years; 113 (95.8%) being 18–44years, and 5 (4.2%): 45–56 years; mostly males, 13 (11.02%) females, all Africans of Yoruba ethnicity.

Estimated reference limits were: Zinc: 9.49–20.54 μmol/L, Selenium: 0.50–1.11 μmol/L, Copper: 13.86–27.97 μmol/L, Iron: 14.19–32.07 μmol/L, Manganese: 6.24–16.37 nmol/L; Magnesium: 0.78–1.62 mmol/L.

Vitamins: A-1.08–2.39 μmol/L; D: 59.89–164.42 μmol/L; E: 7.13–19.45 μmol/L; K: 0.16–0.42 nmol/L; B1: 74.09–201.56 nmol/L; B6: 0.12–0.29 nmol/L; B12: 155.55–407.96 pmol/L; C: 47.74–112.99 μmol/L.

Detected interleukins (IL-1 to IL-18): IL-1: 0.58–1.24 ng/L, IL-2: 0.09–0.18 ng/L, IL-3: 0.39–0.89 ng/L, IL-4: 0.27–0.58 ng/L, ….to IL-18: 0.74–1.56 ng/L.

Conclusions

The RI derived from this study for serum micronutrient, vitamin and interleukin concentrations are the first published for our population. They are in general agreement with those published from other geographical climes but there are differences at the lower and upper limits of the RI. The study reinforces the importance of deriving RI for the population that a clinical laboratory will serve.