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.