Exogenous Biotin May Be Leading You Astray:
A Novel Cause Of Factitious Neonatal Graves’ Disease
Nora E Renthal MD PhD1, Yachana Kataria PhD2, Rosalind S Brown MD1 and Jessica R Smith MD1
1 Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, USA
2Department of Laboratory Medicine, Boston Children’s Hospital, USA
Submission: May 01, 2017; Published: June 08, 2017
*Corresponding author: Jessica R Smith, MD, Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, USA.
How to cite this article: Renthal NE, Kataria YP, Brown RS, Smith JR. Exogenous Biotin May Be Leading You Astray: A Novel Cause Of Factitious
Neonatal Graves’ Disease. Acad J Ped Neonatol. 2017; 5(1): 555710. DOI: 10.19080/AJPN.2017.05.555710
Normal thyroid function is critical for brain development from infancy through early childhood. Accurate assays to measure thyroid function are essential to properly diagnose thyroid disease in this high-risk population. We report an infant who was misdiagnosed with neonatal Graves’ disease and treated with antithyroid drug (methimazole) due to a biotin-streptavidin laboratory artifact.
Neonatal Graves’ disease is a rare form of pediatric hyperthyroidism that occurs in 1-5% of infants born to mothers with Graves’ disease [1,2]. The risk of neonatal Graves’ disease is highest in those infants born to mothers with active or refractory Graves’ disease during pregnancy. However, infants whose mothers have undergone definitive therapy with either radioiodine ablation or surgical thyroidectomy can still be affected.
Neonatal Graves’ disease results from the transplacental passage of maternal thyrotropin receptor antibodies (TRAbs) which stimulate the fetal thyrotropin receptors (TSHR) on the neonatal thyroid gland. Hyperthyroidism can develop in utero, “fetal thyrotoxicosis,” or in the postpartum period, “neonatal thyrotoxicosis.” Hyperthyroidism that develops in utero can lead to prolonged fetal tachycardia and an increased risk of fetal demise or miscarriage [2,3]. After birth, neonatal Graves’ disease is a self-limiting condition as maternal TSH receptor antibodies classically remit within 12 weeks of life. However, if not immediately identified and treated, neonatal thyrotoxicosis can be life threatening.
The diagnosis of neonatal Graves’ disease is made in coordination with a pediatric endocrinologist. Infants with
neonatal Graves typically demonstrate suppressed serum TSH and elevated free T4 and T3 levels. TSH receptor antibodies are also detectable in both the infant and the mother.
Once the diagnosis is confirmed, treatment should be promptly initiated. Therapy includes both hemodynamic stabilization with beta-adrenergic blockade (propranolol/atenolol) and anti-thyroid drug (methimazole) with the goal of achieving rapid euthyroidism. In acutely ill infants, inorganic iodine and glucocorticoids may be required. With clinical stability, frequent laboratory assessments are necessary in order to titrate antithyroid drug, monitor thyroid function and prevent the development of iatrogenic hypothyroidism .
The proper diagnosis of neonatal Graves’ disease is highly reliant on the ability to accurately assess thyroid function. Laboratory interference by heterophile antibodies to both thyroxine and thyrotropin is well reported; however, artifacts that utilize the biotin-streptavidin system are not widely appreciated in pediatrics. We report a case of a 1-week-old neonate treated with high doses of biotin for neurologic stabilization that was misdiagnosed with neonatal Graves’ disease due to biotin-streptavidin laboratory interference.
The patient was delivered by emergency cesarean section
at 31 weeks due to decreased fetal movement. At birth, he had
marked hydrops and required urgent intubation and ventilation
due to severe respiratory depression and lactic acidosis. He
developed seizures, jaundice, tachycardia, and hypertension, and
subsequently, he was administered therapeutic doses of thiamine
(10mg/kg/day) and biotin (8mg/kg/day) for the presumed
diagnosis of pyruvate carboxylase deficiency. Physical examination
was remarkable for upper extremity tremors, but did not identify
orbitopathy or goiter. Thyroid function tests were notable for a
suppressed serum TSH 0.02 mcunit/mL (1.7-9.1), and elevated
serum free T44. 6ng/mL (0.9-2.3 ng/mL) and total T3 >651 ng/
dL (105-245ng/dL) levels, consistent with neonatal thyrotoxicosis
(Figure 1). The diagnosis of neonatal Graves’ disease was strongly
suggested by the infant’s positive TSH receptor antibody titer,
TRAbs >40 IU/L (<1.75).
Of importance, the patient’s mother was treated with thyroid
hormone replacement therapy for chronic lymphocytic thyroiditis
diagnosed four years prior to the pregnancy. It was uncertain as
to whether TRAbs were measured at the time of her diagnosis;
however, maternal TRAbs, obtained during the patient’s
evaluation, were undetectable TRAbs <0.90 IU/L (<1.75 IU/L).
Anti-thyroid medication (methimazole 0.5mg/kg/day) was
initiated on DOL15, and there was a gradual reduction in serum
free T4 and T3 levels (Figure 1). Biotin therapy was discontinued
on DOL19 when a therapeutic effect was not clinically observed.
The patient’s newborn screen (DELFIA Perkin-Elmer), performed
on DOL20, was discordant with serum thyroid function tests
obtained one day prior. On DOL21, the patient was clinically
stable and transferred to another facility. Thyroid function tests,
obtained on DOL 34, were notable for an elevated TSH 34.7
mcunit/mL (1.7-9.1) and normal free T4 0.9 ng/mL (0.9-2.3), and
methimazole was discontinued.
Assays performed at Boston Children’s Hospital (Boston,
MA) and the New England Newborn State Screening Laboratory
(Jamaica Plain, MA). At Boston Children’s Hospital, serum T4, free
T4, T3, and TSH were measured by an electrochemiluminescence
immunoassay on the Cobas Roche analyzer (Indianapolis, IN). TSH
receptor antibody (TBII) was measured at ARUP laboratories (Salt
Lake City, Utah). TSH receptor antibody (TRAb) was measured
by a quantitative electrochemiluminescent immunoassay on the
Cobas Roche analyzer (Salt Lake City, Utah).
Biotin is a water-soluble B-vitamin found naturally in foods,
which acts as a coenzyme in the carboxylation, transcarboxylation,
and decarboxylation reactions of gluconeogenesis, lipogenesis,
fatty acid synthesis, propionate metabolism, and catabolism of
leucine . Biotin is highly concentrated in liver (100mcg per
100g), whereas most other meats contain trace amounts (1mcg
per 100g). Leafy green vegetables, peanuts, and raw egg yolk
also contain large amounts of biotin. Egg whites contain the
protein avidin, which binds strongly to biotin, thus reducing its
bioavailability. A typical Western diet contains adequate amounts
of biotin with a recommended daily intake of 30mcg/day.
Biotin deficiency is rare. Older clinical studies with subjective
measures indicated a potential role for biotin in the improvement
of hair growth, skin radiance, and fingernails . Quality clinical
studies supporting this application are lacking. In the pediatric
population, biotinidase deficiency or partial biotinidase deficiency
can be difficult to diagnose, particularly in the neonatal period.
Presently, high dose biotin (1-6 months: 5mcg/day or ~0.7mcg/
kg/day) is more commonly being used in a neonatal intensive
care unit . In rare cases of refractory juvenile onset myoclonic
dystrophies, a trial of high dose biotin therapy is attempted. In
addition, many adolescents self-administer high dose of biotin (5-
10 grams per day) in an effort to improve hair loss, dry skin and
In-vitro diagnostic platforms take advantage of the biotinstreptavidin
interaction due to its analytical sensitivity, specificity
and ease of performance . Manufacturers add streptavidin to the
assay reagents to scavenge the free biotin and reduce interference
upto a manufactured specified level. However, these assays are
subjected to interference from large doses of biotin and can lead
to aberrant laboratory results. This has recently been reported
in the literature [9-12] and is illustrated in this case of transient
subclinical hypothyroidism resulting from the use of anti-thyroid
medication for a presumed diagnosis of neonatal Graves’ disease.
Several commercially available TSH assays utilize a sandwich
immunoassay, in which biotinylated-capture and labeleddetection
antibodies bind to different epitopes on TSH to form
a sandwich complex. This complex becomes bound to the solid
phase due to the interaction of biotin and streptavidin. Unbound
substances are removed, and bound substances are detected
via chemiluminescent technology. Therefore, the biotinylated
labeled sandwich immunocomplex is directly proportional to the
amount of analyte present in the serum. In this case, the excess
serum biotin present in our patient’s sample resulted in a reduced
sandwich complexes and a falsely low TSH level.
Many of the TBII, free and total thyroxine assays also utilize a
competitive immunochemical assay design. These assays result in
competition between antibody binding of endogenous hormone
and a detectable, biotinylated labeled analyte analogue. The
immunocomplex of biotinylated analogue and antibody is formed
and is inversely proportional to the amount of hormone present in
the sample. Streptavidin on the solid phase immobilizes the labeled
biotinylated analogues. The unbound substances are removed,
and the bound substances are measured via chemiluminescent
technology. Conversely, the excess serum biotin in our patient’s
sample resulted in falsely elevated T4, T3 and TBII concentrations.
Biotin interference also occurs in the measurement of other
competitive assays including testosterone, estrogen and DHEAS.
Therefore, the combination of assay interference with orally
ingested biotin can be misleading and potentially result in the
misdiagnosis of thyrotoxicosis and other endocrinopathies.
In addition to the treatment of children with metabolic and
neurologic disease, biotin is widely available over-the-counter as a
natural supplement. Thus, biotin laboratory interference must be
considered in all patients undergoing any endocrine evaluation,
but particularly thyroid dysfunction, especially when there is a
discrepancy between the clinical scenario and laboratory results.
In this case, the absence of maternal TRAbs was inconsistent
with the diagnosis of neonatal Graves’ disease, leading to the
postulation of biotin interference. In these circumstances, we
recommend evaluating the serum on an alternative platform
(such as the Abbott Architect i1000 platform, which does not have
streptavidin-biotin as part of the system). Alternatively, biotin
interference can be eliminated from an assay by withholding the
supplement for at least 72 hours prior to retesting. Evaluating for
biotin inference leads to an improvement in the interpretation of
thyroid function, patient diagnosis and clinical care. A misdiagnosis
of neonatal Graves’ disease is not benign, as antithyroid
medications can result in iatrogenic hypothyroidism with
potential adverse effects on neonatal growth and neurocognitive
development. Thus, increased awareness of biotin interference is
critical in this age group.