Infection-induced depression of serum retinol—a component of the acute phase response or a consequence?

This issue of the Journal contains closely linked articles by

Mitra et al (1, 2) about acute (but transient) depression of serum

retinol and retinol losses in the urine of children suffering from

dysenteries caused chiefly by

Shigella

species. Whereas these

articles provide new information about pathophysiologic mecha-

nisms that contribute to these infection-induced changes in

retinol metabolism, they also raise important questions about

how these new data are to be interpreted.

The 1968 monograph by Scrimshaw et al (3) reviewed

instances in which severe infections were followed by an abrupt

development of xerophthalmia or other optical manifestations of

vitamin A deficiency. It thus seemed evident that infectious dis-

eases could deplete vitamin A stores by accelerating metabolic

losses, impairing intestinal absorption, or both (3, 4). The con-

cept that infections could deplete hepatic stores of retinol was

strengthened further by Stephensen et al (5), who showed that

vitamin A was lost via the urine in patients with pneumonia or

sepsis. New estimates (2) suggest that urinary losses in children

with severe infection could deplete marginal stores of hepatic

retinol within 1 or 2 wk. But these new data (1, 2) also indicate

that infectious illnesses influence retinol metabolism in ways far

more complex than the simple depletion of vitamin A stores.

Infection-related declines in serum vitamin A have been noted

since the 1950s, with numerous reports this decade (1–4, 6). The

experimental design of Mitra et al’s study (1) was strengthened

by important variables included in their patient population. The

90 children with dysentery ranged in age from 5 mo to 5 y and

had different degrees of preexisting malnutrition and severities

of illness. Dysentery varied with etiology, ie, 66 children (73%)

had

Shigella

infections, and of these, 49 (54%) were infected

with highly virulent

S. dysenteriae

type l strains.

Type 1 strain

Shigella

infections were manifested by high

fevers, higher white cell counts, more prominent acute phase

serum protein responses, more bloody diarrhea, and longer ill-

nesses than those caused by other strains and species of bacteria

(1). In addition, severity of type 1

S. dysenteriae

infections cor-

related with larger depressions in serum retinol, urinary losses of

retinol, and more preexisting malnutrition (as estimated by sev-

eral anthropometric indexes) (1)
 Mau Data Lebih Lengkap
Download disini