Differential Diagnosis
The patient's laboratory results and symptoms suggest a complex endocrine disorder. Here's a categorized differential diagnosis:
Single most likely diagnosis
- Polycystic Ovary Syndrome (PCOS): The patient's irregular periods, elevated androgen levels (DHEAS, 17-hydroxyprogesterone, androstenedione, and testosterone), and normal cortisol and ACTH levels are consistent with PCOS. The mildly elevated prolactin level can also be seen in PCOS.
Other Likely diagnoses
- Hyperprolactinemia: Although the prolactin level is only mildly elevated, it could still be contributing to the patient's irregular periods. Further evaluation may be needed to determine the cause of the hyperprolactinemia.
- Thyroid dysfunction: The patient's TSH and free thyroid hormone levels are within normal limits, but some patients with thyroid dysfunction can have mild abnormalities in these tests. Further evaluation may be needed to rule out thyroid dysfunction.
- Adrenal hyperplasia: The patient's elevated 17-hydroxyprogesterone level could suggest adrenal hyperplasia, but the normal cortisol and ACTH levels make this less likely.
Do Not Miss diagnoses
- Cushing's syndrome: Although the patient's cortisol level is normal, Cushing's syndrome can present with irregular periods, hyperandrogenism, and other symptoms. An MRI may be appropriate to rule out Cushing's syndrome, especially if other symptoms such as weight gain, hypertension, or striae are present.
- Pituitary adenoma: A pituitary adenoma could cause hyperprolactinemia, and some adenomas can produce other hormones, leading to a variety of symptoms. An MRI would be appropriate to rule out a pituitary adenoma.
- Adrenal tumor: An adrenal tumor could cause hyperandrogenism and other symptoms. Although the patient's cortisol level is normal, an adrenal tumor could still be present.
Rare diagnoses
- Congenital adrenal hyperplasia (late-onset): This condition can present with hyperandrogenism and irregular periods, but it is relatively rare.
- Steroidogenic enzyme deficiencies: These rare conditions can cause hyperandrogenism and other symptoms, but they are typically diagnosed in childhood.
- Gonadal dysgenesis: This condition can cause hyperandrogenism and irregular periods, but it is typically diagnosed in childhood or early adolescence.
Regarding the appropriateness of an MRI to rule out Cushing's syndrome, it may be premature at this time. The patient's cortisol level is normal, and there are other more likely explanations for her symptoms. However, if other symptoms suggestive of Cushing's syndrome are present, or if the patient's condition does not respond to treatment for PCOS or other likely diagnoses, an MRI may be warranted to rule out Cushing's syndrome or other pituitary or adrenal disorders.