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Previous issue date: 2015-05-26 === A vitamina A ? um nutriente essencial em diversos processos fisiol?gicos,
como crescimento e desenvolvimento, de modo que um adequado estado nutricional
nesse nutriente ? fundamental na gesta??o e lacta??o. Mulheres lactantes e
crian?as em aleitamento materno s?o consideradas grupos de risco para a
defici?ncia de vitamina A e alguns fatores podem aumentar o risco de
hipovitaminose, como a prematuridade. O objetivo deste trabalho foi avaliar a
concentra??o de vitamina A em lactantes e rec?m-nascidos pr?-termo e a termo, por
meio da determina??o do retinol no soro materno, no soro do cord?o umbilical e no
leite materno coletado at? 72 horas p?s-parto. Foram recrutadas 182 parturientes,
divididas em grupo pr?-termo (GPT; n=118) e grupo termo (GT; n=64). No grupo pr?-
termo tamb?m foram analisadas amostras de leite de transi??o (7?-15? dia; n=68) e
leite maduro (30?-55? dia; n=46). O retinol foi analisado por cromatografia l?quida de
alta efici?ncia (CLAE). A concentra??o materna de retinol s?rico foi 48,6 ? 12,3
?g/dL no GPT e 42,8 ? 16,3 ?g/dL no GT (p<0,01). O retinol no soro do cord?o
umbilical foi 20,4 ? 7,4 ?g/dL no GPT e 23,2 ? 7,6 ?g/dL no GT (p>0,05). Entre os
rec?m-nascidos, 43% dos prematuros e 36% dos a termo apresentaram baixos
n?veis de retinol s?rico no cord?o umbilical (<20 ?g/dL). No colostro, lactantes pr?-
termo e termo apresentaram m?dia de retinol de 100,8 ? 49,0 ?g/dL e 127,5 ? 65,1
?g/dL, respectivamente (p<0,05). A m?dia de retinol no leite pr?-termo aumentou
para 112,5 ? 49,7 ?g/dL na fase de transi??o e reduziu para 57,2 ? 23,4 ?g/dL no
leite maduro, diferindo significativamente entre todas as fases (p<0,05). Ao comparar
com a recomenda??o de ingest?o de vitamina A (400 ?g/dia) o leite colostro do GT
atingiu a recomenda??o para lactentes, por?m no GPT a recomenda??o n?o foi
atingida em nenhuma das fases. As m?es de rec?m-nascidos prematuros possu?am
concentra??o s?rica de retinol superior ? de m?es a termo, entretanto, isso n?o foi
refletido no retinol do soro do cord?o umbilical, uma vez que os prematuros
apresentaram menor concentra??o da vitamina. Tal condi??o pode ser explicada
devido ? menor hemodilui??o fisiol?gica materna e transfer?ncia placent?ria de
retinol para o feto durante a gesta??o pr?-termo. A compara??o do retinol no
colostro evidenciou menor concentra??o no GPT, no entanto na fase de transi??o
houve um aumento importante do conte?do de retinol liberado pela gl?ndula
mam?ria de lactantes pr?-termo. Essa situa??o evidencia uma adapta??o fisiol?gica
pr?pria da prematuridade, provavelmente no sentido de contribuir mais para a
forma??o das reservas hep?ticas de retinol dos lactentes prematuros. === Vitamin A is an essential nutrient for many physiological processes such as
growth and development, so that their adequate nutritional state is essential during
pregnancy and lactation. Lactating women and children in breastfeeding are
considered risk groups for vitamin A deficiency and some factors may increase the
risk of vitamin A deficiency, such as prematurity. The aim of this work was to evaluate
the vitamin A concentration in preterm and term lactating women and newborns by
determination of retinol in maternal serum, umbilical cord serum and breast milk
collected until 72 hours postpartum. 182 mothers were recruited and divided into
preterm group (GPT; n = 118) and term group (GT, n = 64). In preterm group were
also analyzed transition milk (7th-15th day; n = 68) and mature milk (30th-55th day; n
= 46) samples. Retinol was analyzed by high-performance liquid chromatography
(HPLC). Maternal retinol concentration in serum was 48.6 ? 12.3 ?g/dL in GPT and
42.8 ? 16.3 ?g/dL in the GT (p <0.01). Cord serum retinol was 20.4 ? 7.4 ?g/dL in
GPT and 23.2 ? 7.6 ?g/dL in GT (p> 0.05). Among newborns, 43% of premature and
36% of term had low levels of serum retinol in umbilical cord (<20 ?g/dL). In
colostrum, the retinol in preterm and term groups had an average of 100.8 ? 49.0
?g/dL and 127.5 ? 65.1 ?g/dL, respectively (p <0.05). The retinol average in preterm
milk increased to 112.5 ? 49.7 ?g/dL in transition phase and decreased to 57.2 ?
23.4 ?g/dL in mature milk, differing significantly in all stages (p <0.05). When
comparing with the recommendation of vitamin A intake (400 ?g/day) GT colostrum
reached the recommendation for infants, but in GPT the recommendation was not
achieved at any stage. Mothers of premature infants had higher serum retinol than
mothers at term; however, this was not reflected in serum retinol of umbilical cord,
since premature had lower concentration of retinol. Such condition can be explained
due to lower maternal physiological hemodilution and placental transfer of retinol to
the fetus during preterm gestation. Comparison of retinol in colostrum showed lower
concentrations in GPT; however the transition phase there was a significant increase
of retinol content released by the mammary gland of preterm mothers. This situation
highlights a specific physiological adaptation of prematurity, likely to more contribute
to formation of hepatic reserves of retinol in premature infants.
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