Delayed Diagnosis of Congenital Hypothyroidism in a Child with Trisomy 21 and Biotinidase Deficiency and Successful Use of Levothyroxine Sodium Oral Solution
Table 1
Thyroid function tests after diagnosis of biotinidase deficiency.
Weeks of life
Days off biotin
TSH (mIU/mL)
FT4 (ng/dL)
Measured
Normal range
Measured
Normal range
2
0
3.39
0.71–9.34
5.0
0.7–2.4
3
3
5.1
0.71–9.34
2.4
0.7–2.4
8
4
12.9
0.35–5.5
1.6
0.8–1.9
8.5
Patient started on tablet L-T4 25 µg
16
3
0.08
0.35–5.5
2.2
0.8–1.9
Dose of tablet L-T4 reduced to 12.5 µg
20
3
0.04
0.35–5.5
2.4
0.8–1.9
Formulation of L-T4 changed to L-T4 oral solution 13 µg daily
24
4
1.75
0.35–5.5
1.96
0.8–1.9
28
4
3.2
0.35–5.5
0.8–1.9
Normal ranges shown are those used by the author’s institution. FT4, free thyroxine; L-T4, levothyroxine; TSH, thyroid-stimulating hormone.