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Plasma cholesteryl ester transfer protein activity is high in infants and is not affected by thyroid hormones
1Department of Pediatrics, School of Medicine, Niigata University, Japan.
Insights
Thyroid dysfunction does not impact cholesteryl ester transfer protein (CETP) activity in infants. Infant plasma CETP activity is significantly higher than in adults, regardless of thyroid status.
Area of Science:
- Endocrinology
- Lipid Metabolism
- Pediatric Health
Background:
- Cholesteryl ester transfer protein (CETP) plays a crucial role in lipoprotein metabolism.
- The influence of thyroid hormones on CETP activity, particularly in infants, remains incompletely understood.
Purpose of the Study:
- To investigate the effect of thyroid dysfunction on plasma CETP activity in infants.
- To determine if L-thyroxine (LT4) replacement therapy alters CETP activity in hypothyroid infants.
- To examine the relationship between thyroid hormone levels and CETP activity in infants.
Main Methods:
- Plasma CETP activity was measured in hypothyroid infants before and after LT4 treatment, compared to normal infants and adults.
- Thyroid hormone levels (TSH, FT4, FT3) were assessed using an autoanalyzer.
- CETP activity was quantified by the rate of radiolabeled cholesteryl ester transfer.
Main Results:
- No significant difference in plasma CETP activity was observed between hypothyroid and normal infants.
- LT4 replacement therapy did not alter CETP activity in hypothyroid infants.
- Plasma CETP activity was significantly higher in both hypothyroid and normal infants compared to normal adults.
- No correlation was found between CETP activity and serum TSH, FT4, or FT3 levels.
Conclusions:
- Thyroid hormones do not appear to influence plasma CETP activity in infants.
- Infants exhibit inherently higher plasma CETP activity than adults.
- These findings suggest that infant CETP activity is independent of thyroid status.
Abstract:
We investigated the effects of thyroid dysfunction on cholesteryl ester transfer protein (CETP) by studying plasma CETP activity in hypothyroid infants before and after they were rendered euthyroid by L-thyroxine (LT4) replacement therapy. To exclude environmental factors possibly affecting plasma CETP activity, we selected hypothyroid infants to study plasma CETP activity. Plasma CETP activity was measured as the rate of radiolabeled cholesteryl ester transfer from high-density lipoprotein (HDL) to serum apolipoprotein B (apo B)-containing lipoproteins in plasma from 14 hypothyroid infants before and 2 months after LT4 replacement, 23 normal infants, and 61 normal adults. Relationships between CETP and thyroid hormones were examined separately in the 14 hypothyroid infants and 32 euthyroid infants, including the 14 above-described hypothyroid infants and an additional 18 treated hypothyroid infants. Serum levels of thyrotropin (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were also determined on an autoanalyzer system in our hospital. In contrast to previous reports, we found no differences in plasma CETP activity between hypothyroid infants and age-matched normal infants. LT4 substitution did not cause any changes in plasma CETP activity after therapy. Plasma CETP activity showed no correlation with serum TSH, FT4, and FT3 levels. Both hypothyroid and normal infants were found to have significantly higher plasma CETP activity than normal adults. From these results, we conclude that in infants thyroid hormones do not affect plasma CETP activity, and normal infants have high plasma CETP activity, compared with normal adults.