title: Measurement of Serum Free Thyroxine Index May Provide Additional Case Detection Compared to Free Thyroxine in the Diagnosis of Central Hypothyroidism.
abstract: The diagnosis of central hypothyroidism is often suspected in patients with hypothalamic/pituitary pathology, in the setting of low, normal, or even slightly elevated serum TSH and low free thyroxine (FT4). We present four cases of central hypothyroidism (three had known pituitary pathology) in whom central hypothyroidism was diagnosed after the serum free thyroxine index (FTI) was found to be low. All had normal range serum TSH and free thyroxine levels. This report illustrates that the assessment of the serum FTI may be helpful in making the diagnosis of central hypothyroidism in the appropriate clinical setting and when free T4 is in the low-normal range, particularly in patients with multiple anterior pituitary hormone deficiencies and/or with symptoms suggestive of hypothyroidism.
authors.affiliation: Endocrinology and Metabolism Institute, Cleveland Clinic, Desk F-20, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Pantalone
authors.affiliation: Endocrinology and Metabolism Institute, Cleveland Clinic, Desk F-20, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Betul
authors.initials: B
authors.lastname: Hatipoglu
authors.affiliation: Pathology and Laboratory Medicine Institute, Cleveland Clinic, Desk LL3-140, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Manjula K
authors.initials: MK
authors.lastname: Gupta
authors.affiliation: Endocrinology and Metabolism Institute, Cleveland Clinic, Desk F-20, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Laurence
authors.initials: L
authors.lastname: Kennedy
authors.affiliation: Endocrinology and Metabolism Institute, Cleveland Clinic, Desk F-20, 9500 Euclid Avenue, Cleveland, OH 44195, USA; Department of Endocrinology, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Hamrahian