Endocrine Abstracts

Introduction

Clinically functioning gonadotroph adenomas (FGA) are rare, especially in men. We present a case of a LH/FSH-secreting functioning gonadotroph macroadenoma in an elderly patient, which manifested with visual impairment and was accompanied by secondary erythrocytosis.

Clinical case

A 62-y.o. male was admitted to our hospital with a 9-month history of visual impairment and a 5-year history of plethora of the face, neck and upper half of the trunk. Before admission, brain MRI was performed and revealed a pituitary macroadenoma. At admission, MRI confirmed a 40 × 41 × 33 mm pituitary macroadenoma with supra-infra-retro-para (D, S) extension (Knosp IV). Hormonal evaluation revealed secondary hypothyroidism (TSH 0.795 IU/l (0.25–3.5), fT4 6.95 pmol/l (9–19)), normal IGF-1 104.6 ng/ml (16–245) and late-night salivary cortisol 5.11 nmol/l (0.5–9.65). There were high FSH 22.5 IU/l (1.6–9.7) and high-normal LH 10.3 IU/l (2.5–11) and testosterone 28 nmol/l (11–28.2), which allowed us to suspect a FGA. Moreover, there were elevated hemoglobin 196 g/l (132–172), hematocrit 56.7% (40–51) and red-cell count 6.660.000 per mm³ (4.300.000–5.800.000), which was consistent with secondary erythrocytosis due to testosterone excess. On ophthalmological examination bitemporal hemianopsia was found. The patient underwent transnasal transsphenoidal surgery. Before surgery, three procedures of blood exfusion were performed to minimize perioperative risks. Immediately after surgery, there was a rapid decline in FSH 4.19 IU/l, LH 0.513 IU/l and testosterone 0.62 nmol/l. However, secondary hypothyroidism persisted (TSH 0.088, fT4 5.78) and secondary adrenal insufficiency manifested (morning serum cortisol 175.6 nmol/l (171–536)), which required replacement with levothyroxine and hydrocortisone. Transient hyponatremia was also noted. The levels of hemoglobin (152 g/l), hematocrit (44.9%) and red-cell count (5.150.000 per mm³) returned to normal. Immunohistochemical examination of the tumor showed positive FSH expression in 30% of cells and positive LH expression in 80% of cells. Ki-67 index was 3%.

Conclusion

This is a rare case of FGA with predominant LH expression leading to hyperandrogenism and secondary erythrocytosis in an elderly patient. As in the majority of the described cases this case manifested with visual impairment, though signs of erythrocytosis had manifested long before. Though drug-associated secondary erythrocytosis due to testosterone overdose is well studied, the possibility of endogenous testosterone overproduction in patients with erythrocytosis should also be considered.