Serum zinc (Zn) tends to be low in elderly inpatients. Therefore, serum copper (Cu) / zinc (Zn) ratio was examined in elderly ones with enteral liquid foods or with oral diets. In either 396 subjects (143 men, 253 women) with enteral liquid foods or 152 (60 men, 92 women) with oral diets, these subjects were divided into many groups by every 10 μg/dl of serum Cu; 1-10 μg/dl, 11-20 μg/dl, 21-30 μg/dl, 31-40 μg/dl, 41-50 μg/dl, 51-60 μg/dl, 61-70 μg/dl, 71-80 μg/dl, 81-90 μg/dl, 91-100 μg/dl, 101-110 μg/dl, 111-120 μg/dl, 121-130 μg/dl, ≥ 131 μg/dl in enteral liquid foods, and 81-90 μg/dl, 91-100 μg/dl, 101-110 μg/dl, 111-120 μg/dl, 121-130 μg/dl, ≥ 131 μg/dl in oral diets. Furthermore, serum Cu/Zn ratios were investigated in inpatients with various diseases. Serum Cu/Zn ratio became higher significantly by the higher levels of serum Cu, because serum Zn remained almost constant in both enteral liquid foods and oral diets. Serum Cu/Zn ratio of inpatients with diabetes mellitus (7 men, 11 women), chronic renal failure (8 men, 35 women) and hepatic failure (8 women) were examined comparing to serum Cu/Zn ratio of the controls (10 men, 28 women). In inpatients with various diseases who ingested oral diets, serum Cu/Zn ratio was the following orders; the controls < diabetes mellitus < chronic renal failure < hepatic failure, when serum Cu levels were almost constant in the above cases. Therefore, serum Zn levels were lowest in inpatients with hepatic failure.
