A Rare Case of a Plurihormonal Pituitary Adenoma

Background: Pituitary adenomas are usually benign tumors that arise from adenophypophyseal cells and produce one or two types of hormones. Plurihormonal adenomas are a rare subtype that produce two or more hormones and represent less than 1% of all pituitary adenomas.

Clinical Presentation: A 76-year-old female presented for evaluation of abnormal thyroid function test results. She was found to have an elevated free T4 of 1.92 ng/dL and total T4 of 14.4 ug/dL with an inappropriately normal TSH of 2.11 uIU/mL. Physical examination was significant for tachycardia, tremors, diaphoresis, coarse facial features, and enlarged hands. Further biochemical evaluation of her pituitary hormone levels demonstrated an elevated prolactin (PRL) of 237.2 ng/mL, elevated insulin-like growth factor 1 (IGF-1) of 787 ng/mL, normal morning ACTH of 47 pg/mL, normal morning cortisol of 17.0 ug/dL, an inappropriately suppressed FSH of <5.0 mIU/mL, an elevated alpha subunit of pituitary glycoprotein hormones (PGH) of 6.9 ng/mL, and an elevated free T4 of 3.5 ng/dL by equilibrium dialysis. She underwent an MRI of the pituitary and brain which demonstrated a pituitary adenoma measuring 1.2 x 1.3 x 1.8 cm with a portion herniating into the sella turcica with no mass effect of the optic chiasm. A formal visual field examination was normal. The patient underwent workup for Cushing’s Disease with a low dose overnight dexamethasone suppression test, resulting in an appropriate response with an 8 AM cortisol of <1.0 ug/dL. Glucose suppression test confirmed the diagnosis of acromegaly with growth hormone at 120 minutes of 19.90 ng/mL. Neurosurgery performed a trans-sphenoidal pituitary adenoma resection. Thyroid function tests on post-operative day 4 demonstrated a suppressed TSH of 0.01 uIU/mL and an elevated free T4 of 2.30 ng/dL. Histological evaluation revealed dual expression of transcription factors pituitary-specific positive transcription factor 1 (PIT1) and steroidogenic factor 1 (SF1) as well as PRL, GH, TSH and FSH expression. Immunostaining for LH and ACTH were negative. Post-operative IGF-1 and GH levels were 106 ng/mL and 0.51 ng/mL at 17 weeks, respectively. Post-operative TSH normalized to 0.82 uIU/mL, free T4 normalized to 1.04 ng/dL, and PRL normalized to 8.1 ng/mL at 12 weeks. The patient remained symptom free after successful surgical resection.

Discussion: Our case demonstrates the clinical course of a unique patient with clinical and biochemical manifestations of thyroid dysfunction and acromegaly with a pituitary adenoma immunoreactive for GH, TSH, FSH, and PRL. The co-secretion of GH, TSH, PRL, and FSH as well as positivity for the alpha-subunit is extremely unusual. This case emphasizes the importance of considering pituitary abnormalities as a cause for abnormal thyroid function tests.

Metformin Inhibits Mouse Islet Insulin Secretion and Alters Intracellular Calcium in a Concentration-Dependent and Duration-Dependent Manner near the Circulating Range

Metformin is considered the first-line treatment for type 2 diabetes. While metformin primarily increases insulin sensitivity, evidence also suggests that metformin affects the activity of insulin-secreting pancreatic islets. This study was designed to systematically examine the direct effects of metformin by measuring insulin secretion and the kinetics of the calcium response to glucose stimulation in isolated mouse islets using varying concentrations (20 μM, 200 μM, and 1 mM) and durations (~1, 2, and 3 days) of metformin exposure. We observed both concentration- and duration-dependent inhibitory effects of metformin. Concentrations as little as 20 μM (nearing circulating therapeutic levels) were sufficient to reduce insulin secretion following 3-day treatment. Concentrations of 200 μM and 1 mM produced more pronounced effects more rapidly. With 1 mM metformin, islets showed severe impairments in calcium handling, inhibition of insulin secretion, and increased cell death. No stimulatory effects of metformin were observed for any experimental endpoint. We conclude that the direct effects of metformin on islets are inhibitory at near-physiological concentrations. Beneficial effects of metformin observed on islets under various stressors may occur by "resting" fatigued cellular processes. However, metformin may have unintended consequences on normally functioning islets within the circulating range that require further evaluation.

A clinical attempt to avoid hyperacute rejection by F (ab') 2 organ pretreatment

An attempt was made to, in a controlled study, avoid hyperacute rejection by pretreatment of a renal graft pepsine digested anti-donor antibodies. It turned out to be unsuccessful, but there were some indications that the chain of events that leads to the destruction of the graft was delayed for some hours. There may be several reasons for this failure but we think it is possible to improve this method even if its importance in clinical use is still doubtful.