Category: Pituitary Disorders/Neuroendocrinology
Objective : Increased awareness of thorough interpretation and investigation of common initial endocrine testing can lead to diagnosis of significant pathology.
A 32-year-old female presented with a 5-year history of progressively worsening fatigue, cold intolerance, dry skin, and constipation. A few months prior to consultation visit she started taking Meta T supplement which contained bovine thyroid hormone extract. She had some symptomatic relief of her symptoms after she started taking the supplement.
Initial evaluation of thyroid function showed TSH 1.16 u[IU]/mL (0.35-4.01) Free T4 0.7 NG/dL (0.61-1.37). Meta T supplement was discontinued and thyroid function test repeated. It showed normal TSH and low free T4 which increased suspicion for central hypothyroidism. Evaluation of pituitary hormones including Insulin-like growth factor 1, FSH, LH, prolactin and estradiol were within normal limit.
A pituitary MRI was ordered to further evaluate for the cause of this isolated central hypothyroidism. The MRI unexpectedly demonstrated a large pitutary mass measuring 3.7 x 3.9 x 2.7 cm extending from the sella into the suprasellar area, involving the hypothalamus and displacing the mammillary body. It also abutted the cavernous internal carotid arteries and extended to the level of the foramen of Monroe/anterior portion the fornix.
She was subsequently started on adequate levothyroxine replacement and referred to another tertiary care center with specialized neurosurgery facility due to the complexity of the lesion.
Discussion : In our case, despite having a very large pituitary lesion, pituitary hormones were unexpectedly normal apart from a low free T4 level. This prompted further evaluation with imaging that demonstrated the lesion.
Isolated central hypothyroidism is very rare especially with pituitary lesions of this size. In most cases, TSH alone is sufficient to diagnose hypothyroidism but can miss central etiologies such as pituitary masses. Free T4 measurement is imperative in such cases. Obtaining pituitary imaging should be considered in isolated central hypothyroidism.
Ghaydaa Adawi– Endocrinology Fellow, MSU Endocrinology, Holt, Michigan
Atinuke Aluko– Resident, MSU internal medicine, Michigan
Tariq Alrasheed– Endocrinology Fellow, MSU Endocrinology fellowship program
Vengamamba Polu– Fellowship, Michigan State University, Lansing, Michigan
Naveen Kakumanu– Assistant Professor of Medicine, MSU Endocrinology
Saleh Aldasouqi– Professor of Medicine and Chief of Endocrinology, Michigan State Universtiy
Endocrinology fellow at MSU Endocrinology
MSU Endocrinology fellowship program
Currently endocrinology fellow at MSU endocrinology
Michigan State University
I am doing fellowship at Michigan State University
Assistant Professor of Medicine
Dr. Kakumanu joined the Department of Medicine at MSU on October, 2013. He graduated from Saint George’s University, School of Medicine in Grenada. He completed his residency in Internal Medicine at the Detroit Medical Center, Wayne State University and was Chief Medical Resident, ambulatory clinic preceptor at Harper/Hutzel University Hospital, Detroit Medical Center. He completed a Geriatric Fellowship at Wayne State University and received the Lavoisier Cardozo Award for Excellence in Geriatric Medicine. Endocrinology fellowship was completed at Henry Ford Hospital in 2013. He is board certified in Internal Medicine, Geriatric Medicine and Endocrinology. Has presented multiple posters and abstracts at the Endocrine Society, American Association of Clinical Endocrinologists and American Society for Bone and Mineral Research. His specialty in Endocrinology is diverse with interest in thyroid disorders, diabetes and bone metabolism.