Urinary compound W in pregnant women is a potential marker for fetal thyroid function.
OBJECTIVE
Previously we reported 3,3'-diiodothyronine sulfate-like material (compound W) in maternal serum, and studies suggest that compound W is derived from thyroid hormones of fetal origin. In this study we characterized gestational changes of urinary compound W concentrations to correlate with changes in serum concentrations.


METHODS
Urinary samples were collected from 94 women at various gestational ages ranging from 3 to 40 weeks. Urinary compound W was first identified biochemically. The concentrations of compound W (adjusted for creatinine levels) were assessed by a 3,3'-diiodothyronine sulfate radioimmunoassay in ethanol extracts of urine samples.


RESULTS
Compound W increased to 88 +/- 1.4 pmol (of 3,3'-diiodothyronine sulfate equivalent)/mmol creatinine in urinary samples obtained from 26 women in the first trimester of pregnancy compared with 40 +/- 6.9 pmol/mmol creatinine in 10 nonpregnant women. Excretion of compound W increased further during the second and third trimesters: 171 +/- 17 (n = 18) and 434 +/- 26 (n = 50) respectively. In contrast, urinary 3,3',5-triiodothyronine sulfate concentrations measured by radioimmunoassay were similar during pregnancy to values in nonpregnant women.


CONCLUSIONS
Urinary compound W concentrations increase with the progression of normal pregnancy and correlate with the increase in serum levels. Random spot urine compound W concentrations, adjusted for creatinine levels, may be used in place of serum levels in conditions in which obtaining serum samples may be technically difficult, especially during population screening.
Wu
S Y
SY
Nuclear Medicine and Medical Services, Veterans Administration Medical Center, Long Beach, California 90822, USA.
Fisher
D A
DA
Huang
W S
WS
Beck-Peccoz
P
P
Emerson
C H
CH
Kuo
S W
SW
Chen
W L
WL
D015415:Biomarkers / Q000652:urine*; D003404:Creatinine / Q000652:urine; D004104:Diiodothyronines / Q000652:urine; D005260:Female; D005315:Fetal Diseases / Q000652:urine; D005865:Gestational Age; D006801:Humans; D007037:Hypothyroidism / Q000652:urine; D011247:Pregnancy; D011863:Radioimmunoassay; D012016:Reference Values; D013961:Thyroid Gland / Q000196:embryology* / Q000502:physiology*
D015415:Biomarkers; D004104:Diiodothyronines; C404304:compound W; C045738:3,3'-diiodothyronine-4-sulfate; D003404:Creatinine