Category: Pituitary Disorders/Neuroendocrinology
Primary hypothyroidism and pituitary hyperplasia has been reported in literature in both children and adults. We report a case of young male initially diagnosed with pituitary adenoma and then on evaluation found to have profound hypothyroidism.
Our patient is a 28 year old man who presented for the evaluation of a pituitary mass that was discovered incidentally after he underwent a brain CT due to head injury. Subsequently on MRI the mass measured 14mmx14mmx22 mm. Upon questioning the patient complained of fatigue and weight gain but denies any visual disturbances, nipple discharges, polyuria, polydipsia, any increase in shoe size or any organ size, hands or feet, sexual difficulties, constipation, cold or heat intolerance.
The patient seems apathetic and sluggish. He has very dry skin. His brachial and patellar reflexes showed delayed relaxation phase.
He had an ophthalmology assessment for visual field, which was normal.
On laboratory evaluation his FT4 was 0.27ng/dl (0.76-1.46), TSH was >100mIU/ml. Thyroid antibodies were requested.
Other work up revealed Low Testosterone level 49ng/dL ( 264-916) with FSH 4.8 mIU/ml (1.5-12.4) / LH 3.4mIU/ml (1.7-8.6). Morning serum cortisol and IGF-1 were normal. Prolactin was minimally elevated to 48.4 ng/ml (4.0-15.2).
Based on clinical, laboratory and radiological findings, a diagnosis of primary hypothyroidism was made with pituitary macro adenoma which is most likely not functional.
Patient was started on levothyroxine replacement therapy of 150mcg daily.
His follow up MRI after one month of thyroxine replacement showed shrinkage of pituitary adenoma to 17mmx13mmx16mm.
This patient pituitary macroadenoma could be just hyperplasia from severe hypothyroidism as seen in many other physiological conditions like pregnancy, lactation or some pathological conditions.
On MRI, it is difficult to distinguish adenoma from hyperplasia so careful clinical and laboratory evaluation is necessary before proceeding to definitive surgical treatment. As symptoms of hypothyroidism are very vague and non-specific so it can be missed very easily by clinicians and patients.
Despite the initial diagnosis of pituitary macro adenoma, complete endocrine work up and through history established the diagnosis of primary hypothyroidism. In an appropriate clinical setting it is prudent to recognize that the pituitary enlargement can be caused by excessive hormonal secretion and loss of negative feedback. Thyroid replacement therapy and follow up imaging can save a patient from unnecessary procedures or medical therapies.
Huntington, West Virginia
First year fellow at Marshall university Huntington west Virginia