Case History/Examination:
A 24-year-old female with no comorbidities presented with complaints of Galactorrhea and menstrual irregularities for 1.5 years. She had been using norethisterone for her menstrual issues. She reported a weight gain of 20 kilograms over the past 18 months, accompanied by polyuria, mild headache, myalgia, and numbness in her upper limbs. She had a history of delivering a child via C-section 3 years ago but had no other notable past medical or surgical history. Physical examination was unremarkable.
Her complete pituitary profile was checked, which showed high TSH and low Free T4. Her lab results are shown in the table below (Table 1).
These labs were significant for hypothyroidism, so there was a suspicion of pituitary hyperplasia with hypothyroidism, but prolactin levels were also high, so the possibility of pituitary macroadenoma could not be ruled out completely
An MRI of the brain was done a few days before her presentation in the clinic. It showed an enhancing mass in the sellar and suprasellar locations, measuring 11x 16 x 14 mm (AP x TR x CC). An associated mass effect causing downsloping of the sellar floor into the sphenoid sinus was noted. The mass was also compressing the pituitary stalk. Findings were suggestive of pituitary macroadenoma. Images of the MRI brain are shown below in Figures 1 and 2.
As per the multidisciplinary team meeting, it was planned to start her on levothyroxine 100mcg daily and assess the response in an interval MRI brain in 2 to 3 months. Hence, she was advised levothyroxine, which she took regularly with good compliance.
MRI of the brain repeated after 2 months showed interval resolution of the enlarged pituitary gland. It measures 5.7 x 9x 12 mm (CC x AP x Transverse) against the previous 14 x 10 x 17mm measurements. It showed a good treatment response to levothyroxine. Radiological images of the MRI brain are shown below. The arrow shows the complete resolution of the mass shown before (Figures 3 and 4).  
After starting levothyroxine, the patient’s symptoms resolved significantly. Her menstrual cycle normalized, and she became pregnant with her second child. The pregnancy was uneventful, resulting in the delivery of a healthy baby. Her issues with galactorrhea and body pain also resolved. She was advised to return for a follow-up MRI in four months; however, she missed this appointment due to her pregnancy. Lab results showed marked improvement after two months, especially in her TSH levels (Table 2).