Differential Diagnosis
The patient presents with low FSH, LH, and TSH levels, along with a prolactin level of 1128ng/L. Here's a categorized differential diagnosis:
Single Most Likely Diagnosis
- Prolactinoma: The significantly elevated prolactin level is highly suggestive of a prolactinoma, a type of pituitary tumor that secretes prolactin. This condition can suppress the secretion of other pituitary hormones, leading to low FSH, LH, and TSH levels.
Other Likely Diagnoses
- Non-functioning Pituitary Tumor: Although non-functioning pituitary tumors do not secrete hormones, they can compress surrounding pituitary tissue, leading to hypopituitarism, which could explain the low FSH, LH, and TSH levels. However, the prolactin level might be mildly elevated due to stalk effect.
- Craniopharyngioma: This type of brain tumor can compress the pituitary gland and stalk, leading to hypopituitarism. The elevated prolactin could be due to stalk effect, similar to non-functioning pituitary tumors.
Do Not Miss Diagnoses
- Pituitary Apoplexy: Although less likely, pituitary apoplexy (a sudden hemorrhage or infarction of the pituitary gland) is a medical emergency that can present with acute hypopituitarism. The significantly elevated prolactin level might not be typical, but it's crucial to consider this diagnosis due to its urgency.
- Hypothalamic Disease: Diseases affecting the hypothalamus can lead to hypopituitarism. While less common, conditions like hypothalamic tumors or infiltrative diseases (e.g., sarcoidosis, histiocytosis) could explain the hormonal abnormalities.
Rare Diagnoses
- Rathke's Cyst: A rare, benign cystic lesion in the sellar region that can compress the pituitary gland, leading to hypopituitarism. However, it's less likely to cause a significantly elevated prolactin level.
- Lymphocytic Hypophysitis: An autoimmune inflammation of the pituitary gland that can cause hypopituitarism. It's a rare condition and might not typically present with such a high prolactin level.