What is the best-fitting regression line relating mean thyroxine level to gestational age?

Pediatrics, Endocrinology

Transient hypothyroxinemia, a common finding in premature infants, is not thought to have long-term consequences or to require treatment. A study was performed to investigate whether hypothyroxinemia in premature infants is a cause of subsequent motor and cognitive abnormalities [16]. Blood thyroxine values were obtained on routine screening in the first week of life from 536 infants who weighed 2000 g or less at birth and were born at 33 weeks gestation or earlier. The data in Table 11.21 were presented concerning the relationship between mean thyroxine level and gestational age.

Table 11.21 Relationship between mean thyroxine level and gestational age among 536 premature infants

(x) _______________________________________ (y)

Gestational age (weeks) ___________Mean thyroxine level (μg/dL)

≤ 24^a …………………………………………….. 6.5

25 ……………………………………………….. 7.1

26 ……………………………………………….. 7.0

27 ……………………………………………….. 7.1

28 ……………………………………………….. 7.2

29 ……………………………………………….. 7.1

30 ……………………………………………….. 8.1

31 ……………………………………………….. 8.7

32 ……………………………………………….. 9.5

33 ……………………………………………... 10.1

^aTreated as 24 in subsequent analyses.