DYNAMICS OF THE GOITROGEN-IODINE BALANCE IN THE THYROID STATUS OF CATFISH (Clarias guriepinusy FROM FRESH AND-BRACKlSH WATER BODIES IN ONDO STATE

Abstract

The study was designed to investigate the dynamics of the goitrogen-iodine balance in Igbokoda brackish and Ogbese fresh water bodies in Ondo State, Nigeria The parameters determined include proximate composition, iodine, thiocyanate, i chlorides, calcium, zinc, iron, nitrates, magnesium, phosphorus and total coliform count in water/sediment and/or fish (flesh and serum). The fish were subjected to a number of treatments (boiling with water or sodium chloride solution, frying or roasting) prior III analysis. The highest protein concentrations (%) (Ogbese, 73.25; Igbokoda, 7252) of fish samples were recorded by boiling with water while the ones roasted recorded the least '" values of 57.51 % and 58.33 %, respectively. The iodine level (/-lg III OOg) in the flesh of fish varied with size, treatment and location; increased with size, reduced by some . treatments (boiling with either water or NaCI solution) while frying and roasting did not affect the concentration. The least values were 93.45 (Ogbese fish boiled with NaCI solution) and 1·6094 (Igbokoda fish boiled with either water or NaCi solution). On the whole, Igbokoda (160.94-314.08) had 'higher values than Ogbese (93.45-205.0h) Serum iodine (ug I1100mL) was equally higher in Igbokoda (5.00-9.00) compared to Ogbese (2.80-5.00). Only the large sized fish of Ogbese recorded a value of 500 umol/L for thiocyanate while this parameter was not detected in other samples. The levels (mgIL) of minerals in the fish serum from Ogbese were 1002.3] -3979.00 (Na), 87.36-347.10 (K), 687.64-271350 (CI), 400-1500 (Mg) and 25.00-98.00 (Ca) while those of Igbokoda were 1064.90-4232.00 (Na), 104.13-412.23 (K), 930.10-3692.00 (CI), 5.00-18.00 Mg) and '28.00-113.00 (Ca) In both locations, the various treatments reduced the levels of minerals in the edible portion of fish except roasting, which either maintained or elevated the levels. The calculated I1goitrogen ratios (Ilea, lIN03, lie I and liSeN) were higher for Igbokoda water compared to Ogbese water with the exception of IIMg. This was equally reinforced by the total count of coliforms (goitrogenic), which was higher in Ogbese (3.0xl 03) than Igbokoda (2.7xl03). Though fish remains a primary source of iodine, the results of this study indicate that the Igbokoda water body would serve this purpose better than the Ogbese I) i' ... water body, particularly considering the iodine-goitrogen balance. This, by extension, would affect negatively the thyroid status of' the human population dependent on the Ogbese water body.