Reference ranges for serum cortisol and 17-hydroxyprogesterone levels in preterm infants

The use of an early ACTH test to identify hypoadrenalism-related hypotension in low birth weight infants

“…15,16,24 For example, Heckmann et al 16 measured cortisol in medically stable preterm infants with a GA of <30 weeks during the first two weeks of life. Cortisol levels ranged from 66 to 744 nmol l À1 in this cohort.…”

“…Cortisol levels ranged from 66 to 744 nmol l À1 in this cohort. Saedi et al 15 developed reference ranges for serum cortisol with sera from 39 healthy preterm infants <31 weeks of GA, with levels ranging from 20 to 688 nmol l À1 . Both low and high cortisol levels were associated with sickness and poor outcome in preterm infants.…”

“…13 As a result, random cortisol levels used as a marker for adrenal insufficiency are not adequate, particularly as 'normal' cortisol levels in premature babies vary greatly. [14][15][16] Because of the lack of an obvious cutoff level of cortisol upon which clinicians can diagnose adrenal insufficiency early in preterm infants, a stimulation test, that is, adrenocorticotropin hormone (ACTH) test, may be a more accurate measure of adequacy of adrenal function. ACTH tests have been shown to have higher sensitivity for identifying adrenal insufficiency during critical illnesses.…”

The challenge of defining relative adrenal insufficiency

“…[1][2][3] In preterm infants, numerous confounding factors make the definition more elusive. Preterm infants developmentally may have low basal cortisol levels in the absence of symptomatology, 4 and it is less clear what constitutes an appropriate stress response in the face of an acute illness, such as respiratory distress syndrome or sepsis. 5,6 Similarly, many of the symptoms of relative adrenal insufficiency, such as hypotension and electrolyte abnormalities, are common in this population, with many possible underlying etiologies.…”

Stress and severity of illness in very low birth weight infants: what are we measuring?

“…In utero, cortisol concentrations are very low and can remain low in healthy preterm infants without demonstrating evidence of relative adrenal insufficiency. 9,10 Other infants will have low cortisol concentrations in the face of significant cardiorespiratory illness, which has been associated with an increased risk of developing bronchopulmonary dysplasia. [11][12][13][14] Despite this, prophylactic supplementation with hydrocortisone in high-risk infants did not reduce the incidence of bronchopulmonary dysplasia.…”