Plasma concentration, urinary excretion and renal clearance of L-carnitine during pregnancy: a reversible secondary L-carnitine deficiency.
Plasma concentration, urinary excretion and renal clearance of free, total and esterified L-carnitine were monitored monthly in 14 women during the last 6 months of pregnancy and 1 month after delivery. Plasma concentration and renal clearance measured 1 month after delivery overlapped with normal values for females of comparable age, and were considered the reference values for further comparisons. Plasma concentration of free, total and esterified L-carnitine decreased during pregnancy, reaching values as low as half of those measured 1 month after delivery, whereas urinary excretion and renal clearance, mainly of L-carnitine esters, increased, with renal clearance reaching a peak at the 16th week of pregnancy. Pregnancy thus leads to a reversible secondary deficiency of L-carnitine. The involvement of L-carnitine in the excretion of an excess of acyl-S-coenzyme A groups to prevent a possible systemic acidosis, as well as hormonal changes and a reduction of L-carnitine biosynthesis, could play a significant role in the variations in L-carnitine metabolism encountered in pregnancy. As physiological components of L-carnitine are excreted via a saturable tubular reabsorption, their threshold seems to follow plasma concentration, even when they decrease markedly, as in pregnancy.
Marzo
A
A
Drug Metabolism and Pharmacokinetic Department, Sigma-Tau S.p.A., Pomezia, Rome, Italy.
Cardace
G
G
Corbelletta
C
C
Pace
S
S
D'Iddio
S
S
Verrotti
C
C
Cavatorta
E
E
Grignaffini
A
A
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002331:Carnitine / Q000097:blood / Q000172:deficiency / Q000652:urine; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism*
D002331:Carnitine