Acute phase proteins serum concentrations in children are related to urinary iodine excretion

Lialikau SA, Haurylik LL, Sobieska M, Klachko NM, Samborski W

Abstract

Purpose: The paper presents links between iodine provision and selected acute phase proteins’ (APP) serum concentrations as well as their glycosylations profiles (investigated with the use of affinity immunoelectrophoresis with Concanavalin A as ligand) in children. 
Material and method: 116 children (58 girls and 58 boys) were enrolled. Iodine level was measured in the morning (7:30-8:30) urine portion, using Cr-As method. According to iodine level children were divided into two groups. The first one consisted of 56 children with decreased iodine level (lower than 100 micrograms/L), second – 60 children with iodine level higher than 100 micrograms/L. In serum the concentration of ferritin, beta2-microglobulin (beta2-MG), thyroxin (T4), triiodothyronin (T3), thyrotrophic hormone (TSH) were measured by radioimmunoassay (BELORIS, Belarus). Concentrations of APP: C-reactive protein (CRP), alpha1-acid glycoprotein (AGP), alpha1-antichymotrypsin (ACT), alpha1-antitrypsin (AT), haptoglobin (Hp), alpha2-macroglobulin (A2-M), ceruloplasmin (Cp) and transferrin (Tf) were measured in sera samples by rocket immunoelectrophoresis acc. to Laurell with antibodies and standard from DakoCytomation, Denmark. Microheterogeneity of AGP, ACT and Tf was estimated using affinity immunoelectrophoresis with ConA as a ligand, acc. to Břg-Hansen.
Results: It was established, that CRP level was lower than upper limit of normal range. Levels of other investigated proteins were reliably dependent on the level of iodine. Especially for AGP lower level was observed for children of the group with low iodine level. In children with low iodine level along with the decrease of serum AGP concentration altered glycosylations profile was observed, namely decrease in the content of variant  non-reactive to ConA (W0) and increase in content of weakly reactive (W1) and reactive (W2) variants content, which resulted in increase of the reactivity coefficient (AGP-RC). Similar tendency in alterations of distinctly glycosylated variants in relation to iodine level could be shown for ACT. Serum concentration of any investigated protein was not dependent on the concentration of the hormones of pituitary-thyroid system.
Conclusions: It seems that the influence of the iodine level is direct, not via thyroid hormones. It could be suggested that in euthyroid children with low iodine excretion with urine a hidden iodine deficiency is already registered by the regulatory mechanisms and a kind of acute phase reaction is started, may be in order to increase iodine uptake and storage.

Key words: 	iodine provision, thyroid hormones, acute phase proteins.