Abstract
BACKGROUND: Infants born at extreme prematurity (below 28 weeks' gestation) are
at high risk of developmental disability. A major risk factor for disability is
having a low level of thyroid hormone which is recognised to be a frequent
phenomenon in these infants. At present it is unclear whether low levels of
thyroid hormone are a cause of disability, or a consequence of concurrent
adversity.
METHODS: We propose an explanatory multi-centre double blind randomised
controlled trial of thyroid hormone supplementation in babies born below 28
weeks' gestation. All infants will receive either levothyroxine or placebo until
32 weeks' corrected gestational age. The primary outcome will be brain growth.
This will be assessed by the width of the sub-arachnoid space measured using
cranial ultrasound and head circumference at 36 weeks' corrected gestational. The
secondary outcomes will be (a) thyroid hormone concentrations measured at
increasing postnatal age, (b) status of the hypothalamic pituitary axis, (c)
auxological data between birth and 36 weeks' corrected gestational age, (d)
thyroid gland volume, (e) volumes of brain structures (measured by magnetic
resonance imaging), (f) determination of the extent of myelination and white
matter integrity (measured by diffusion weighted MRI) and brain vessel morphology
(measured by magnetic resonance angiography) at expected date of delivery and (g)
markers of morbidity including duration of mechanical ventilation and chronic
lung disease.We will also examine how activity of the
hypothalamic-pituitary-adrenal axis modulates the effects of thyroid
supplementation. This will contribute to decisions about which confounding
variables to assess in large-scale studies.
TRIAL REGISTRATION: Current Controlled Trials ISRCTN89493983.
at high risk of developmental disability. A major risk factor for disability is
having a low level of thyroid hormone which is recognised to be a frequent
phenomenon in these infants. At present it is unclear whether low levels of
thyroid hormone are a cause of disability, or a consequence of concurrent
adversity.
METHODS: We propose an explanatory multi-centre double blind randomised
controlled trial of thyroid hormone supplementation in babies born below 28
weeks' gestation. All infants will receive either levothyroxine or placebo until
32 weeks' corrected gestational age. The primary outcome will be brain growth.
This will be assessed by the width of the sub-arachnoid space measured using
cranial ultrasound and head circumference at 36 weeks' corrected gestational. The
secondary outcomes will be (a) thyroid hormone concentrations measured at
increasing postnatal age, (b) status of the hypothalamic pituitary axis, (c)
auxological data between birth and 36 weeks' corrected gestational age, (d)
thyroid gland volume, (e) volumes of brain structures (measured by magnetic
resonance imaging), (f) determination of the extent of myelination and white
matter integrity (measured by diffusion weighted MRI) and brain vessel morphology
(measured by magnetic resonance angiography) at expected date of delivery and (g)
markers of morbidity including duration of mechanical ventilation and chronic
lung disease.We will also examine how activity of the
hypothalamic-pituitary-adrenal axis modulates the effects of thyroid
supplementation. This will contribute to decisions about which confounding
variables to assess in large-scale studies.
TRIAL REGISTRATION: Current Controlled Trials ISRCTN89493983.
| Original language | English |
|---|---|
| Journal | Trials |
| Volume | 9 |
| Issue number | 17 |
| Publication status | Published - 2008 |