Pediatric Annals

LETTER TO THE EDITOR 

LIPID PROFILE CHANGES IN YOUNG CHILDREN TREATED FOR HYPOTHYROIDISM

Albert F DiNicola, MD; Vahid Mahabadi, MD; Belal Afridi, MD; Dennis Gelyana, MD

Abstract

To the Editor:

We would like to comment on Dr. McCrindle's excellent review of hyperlipidemia and atherosclerosis in the August 2000 issue.1

Fluctuations of lipid levels before and during treatment with L-thyroxine sodium in young children with severe hypothyroidism are not well studied. Given the early atherosclerotic changes associated with total and low-density lipoprotein (LDL) cholesterol levels in children at autopsy,2 the effect of therapy with L-thyroxine sodium on lipid profile parameters in prepubertal children with profound primary hypothyroidism is important in understanding factors influencing these changes.

The table presents the results of two cases we have studied. Case 1 was an Asian girl who was 6 years, 6 months old. She had profound primary hypothyroidism that was treated with 3.1 ;/g/kg/d of L-thyroxine sodium (100 µg/d). Case 2 was a Hispanic girl who was 5 years, 10 months old. She had profound primary hypothyroidism that was treated with 5.3 µg/kg/d of L-thyroxine sodium (100 µg /d).

These data suggest that (1) normalization of serum thyroxine and thyroid-stimulating hormone in young children with profound primary hypothyroidism appears to result in significant decreases in serum cholesterol (normal range < 175), LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and LDL cholesterol and HDL cholesterol ratios; and (2) lipid profile parameters should be done for children with hypothyroidism before and during therapy with L-thyroxine sodium. Does undiagnosed or suboptimally managed hypothyroidism in children contribute in a significant way to unwanted early atherosclerotic changes?

Table

REFERENCES

1. McCrindle BW. Screening and management of hyperlipidemia in children. PediatrAnn. 2000^9:500-508.

2. Newman WP, Freeman DS, Voors AW, et al. Relation of serum lipoprotein levels and systolic blood pressure to early atherosclerosis: the Bogalusa Heart Study. N Engi / Med. 1986;314:138-144.

Albert F. DiNicola, MD

Vahid Mahabadi, MD

Belai Afridi, MD

Dennis GeIy ana, MD

Naval Hospital

Camp Pendleton, California

Dr. McCrindle responds;

The observation by Dr.

DiNicola and colleagues clearly illustrates an important point in the evaluation and management of hyperlipidemia in children. Secondary causes of hyperlipidemia are important to identify, and can be adequately screened by careful history and physical examination and judicious laboratory testing. Treatment should then be directed at the secondary cause, which usually ameliorates the hyperlipidemia.

Hypothyroidism is an important cause of reversible hyperlipidemia.1 The impact of subclinical hypothyroidism is more controversial.2 To date, no child referred to our Pediatrie Lipid Disorders Clinic for evaluation has been found to have subclinical hypothyroidism as the cause of his or her hyperlipidemia, although one adolescent with familial hypercholesterolemia has incidentally developed subclinical hypothyroidism.

Persistence of hyperlipidemia after adequate treatment of a secondary cause may suggest a primary mechanism that may require treatment directed at the hyperlipidemia itself. The atherogenic risk of hyperlipidemia depends on the type and magnitude of lipid elevations, with elevations in low-density lipoprotein (LDL) cholesterol having the most importance. The risk does not appear to be influenced by the mechanism causing the hyperlipidemia (whether primary or secondary), although this is the subject of current research.

REFERENCES

1. Mishdel MA, Crowther SM. Hypothyroidism, an important cause of reversible hyperlipidemia. Clinica Chimica Acta. 1977;74:139-151.

2. Bogner U, Arntz HR, Peters H, Schleusener H. Subclinical hypothyroidism and hyperlipoproteinaemia: indiscriminate L-thyroxine treatment not justified. Acta Endocrinologia (Copenhagen). 1993;128:202-206.

TABLE

LIpId Profile Changes Associated With L-thyroxine Sodium…

To the Editor:

We would like to comment on Dr. McCrindle's excellent review of hyperlipidemia and atherosclerosis in the August 2000 issue.1

Fluctuations of lipid levels before and during treatment with L-thyroxine sodium in young children with severe hypothyroidism are not well studied. Given the early atherosclerotic changes associated with total and low-density lipoprotein (LDL) cholesterol levels in children at autopsy,2 the effect of therapy with L-thyroxine sodium on lipid profile parameters in prepubertal children with profound primary hypothyroidism is important in understanding factors influencing these changes.

The table presents the results of two cases we have studied. Case 1 was an Asian girl who was 6 years, 6 months old. She had profound primary hypothyroidism that was treated with 3.1 ;/g/kg/d of L-thyroxine sodium (100 µg/d). Case 2 was a Hispanic girl who was 5 years, 10 months old. She had profound primary hypothyroidism that was treated with 5.3 µg/kg/d of L-thyroxine sodium (100 µg /d).

These data suggest that (1) normalization of serum thyroxine and thyroid-stimulating hormone in young children with profound primary hypothyroidism appears to result in significant decreases in serum cholesterol (normal range < 175), LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and LDL cholesterol and HDL cholesterol ratios; and (2) lipid profile parameters should be done for children with hypothyroidism before and during therapy with L-thyroxine sodium. Does undiagnosed or suboptimally managed hypothyroidism in children contribute in a significant way to unwanted early atherosclerotic changes?

Table

TABLELIpId Profile Changes Associated With L-thyroxine Sodium

TABLE

LIpId Profile Changes Associated With L-thyroxine Sodium

REFERENCES

1. McCrindle BW. Screening and management of hyperlipidemia in children. PediatrAnn. 2000^9:500-508.

2. Newman WP, Freeman DS, Voors AW, et al. Relation of serum lipoprotein levels and systolic blood pressure to early atherosclerosis: the Bogalusa Heart Study. N Engi / Med. 1986;314:138-144.

Albert F. DiNicola, MD

Vahid Mahabadi, MD

Belai Afridi, MD

Dennis GeIy ana, MD

Naval Hospital

Camp Pendleton, California

Dr. McCrindle responds;

The observation by Dr.

DiNicola and colleagues clearly illustrates an important point in the evaluation and management of hyperlipidemia in children. Secondary causes of hyperlipidemia are important to identify, and can be adequately screened by careful history and physical examination and judicious laboratory testing. Treatment should then be directed at the secondary cause, which usually ameliorates the hyperlipidemia.

Hypothyroidism is an important cause of reversible hyperlipidemia.1 The impact of subclinical hypothyroidism is more controversial.2 To date, no child referred to our Pediatrie Lipid Disorders Clinic for evaluation has been found to have subclinical hypothyroidism as the cause of his or her hyperlipidemia, although one adolescent with familial hypercholesterolemia has incidentally developed subclinical hypothyroidism.

Persistence of hyperlipidemia after adequate treatment of a secondary cause may suggest a primary mechanism that may require treatment directed at the hyperlipidemia itself. The atherogenic risk of hyperlipidemia depends on the type and magnitude of lipid elevations, with elevations in low-density lipoprotein (LDL) cholesterol having the most importance. The risk does not appear to be influenced by the mechanism causing the hyperlipidemia (whether primary or secondary), although this is the subject of current research.

REFERENCES

1. Mishdel MA, Crowther SM. Hypothyroidism, an important cause of reversible hyperlipidemia. Clinica Chimica Acta. 1977;74:139-151.

2. Bogner U, Arntz HR, Peters H, Schleusener H. Subclinical hypothyroidism and hyperlipoproteinaemia: indiscriminate L-thyroxine treatment not justified. Acta Endocrinologia (Copenhagen). 1993;128:202-206.

TABLE

LIpId Profile Changes Associated With L-thyroxine Sodium

10.3928/0090-4481-20001101-03

Sign up to receive

Journal E-contents