Micronutrient levels vary in patients with Down syndrome
Patients with Down syndrome (DS) have lower blood concentrations of zinc, selenium and calcium, and higher blood cell levels of copper and zinc, according to a systematic review.
Studies that measured micronutrient levels in whole blood, hair, saliva, red cell, serum and plasma samples of DS patients and controls were searched from the databases of PubMed, Web of Knowledge and Scopus. Those that measured protein and mRNA expression were excluded. A total of 69 studies met the inclusion criteria.
The Newcastle-Ottawa scale was used to assess methodological quality of the eligible observational studies. Information extracted from the studies included type of specimen, study sample characteristics, assay used and micronutrient levels.
Five comparisons (cases n=83; controls n=125) showed that red blood cell (RBC) levels of copper were significantly higher in patients with DS than in controls (standardized mean difference [SMD], 2.77; 95 percent CI, 1.96 to 3.57; p<0.00001).
Selenium concentration in the blood (SMD, -0.99; -1.55 to -0.43; p=0.0006), serum (SMD, -0.60; -0.97 to -0.23; p=0.001) and whole blood (SMD, -2.60; -3.32 to -1.89; p<0.00001) were significantly lower in DS cases.
Additionally, while blood calcium was significantly lower in DS cases (SMD, -0.63; -1.16 to -0.09; p=0.02), salivary levels were significantly higher (SMD, 0.85; 0.38 to 1.33; p=0.0004). Salivary sodium was significantly elevated in DS cases (SMD, 1.04; 0.39 to 1.69; p=0.002).
Blood (SMD, -1.30; -1.75 to -0.84; p<0.00001), plasma (SMD, -1.23; -1.93 to -0.54; p=0.0005), serum (SMD, -1.44; -1.93 to -0.95; p<0.00001) and hair (SMD, -0.54; -0.97 to -0.12; p=0.01) zinc concentrations were significantly lower in patients with DS, while RBC zinc (SMD, 2.62; 1.59 to 3.66; p<0.00001) was higher.