AGE AND SEX ARE IMPORTANT FACTORS IN DETERMINING NORMAL RETINOL LEVELS

Cut-off levels for serum retinol levels of 20 mu g/dl for marginal and 10 mu g/dl for definite deficiency have been advocated and extensivel y used in population studies. However, the blood serum levels of retin ol of the newborn are known to be very low and although the age depend ency of the retinol binding protein has been described, the normal lev els of serum retinol at different ages have not been reported from lar ger series, While studying poor populations of young infants in Lahore , Pakistan, we thought it necessary to try to achieve appropriate refe rence values by analysing the levels of serum retinol of expatriates f rom the Indian subcontinent who live in the affluent United Arab Emira tes, where retinol deficiency is not seen either at the hospital or th e community level. We have studied maternal, cord blood, infantile and adult levels of retinol and found a highly significant age relationsh ip of serum retinol levels. During very early infancy the 'normal' mea n Is below what has been considered deficiency. This is new informatio n and important in the evaluation of retinol status of individuals as well as populations. In addition, we found lower levels in women, preg nant or non-pregnant, than those in adult men. This sex difference in adults was not seen in infants. We recommend a cut off level for defic iency of 10 mu g/dl, but only for those above 1 month of postnatal age .