NU680 Unit 7 Diagnostic Reasoning Paper Example

Milk Without a Baby and a Thyroid Nobody Checked: A Unit 7 Diagnostic Reasoning Paper on a Raised Prolactin

[Student Name]

Purdue University Global

NU680: Gynecological, Reproductive, and Sexual Health

Unit 7 Diagnostic Reasoning Paper

[Instructor Name]

[Date]

The patient is composite; her values are illustrative; the sources cited are real.

The Presentation

Ms. Haverford noticed a milky fluid on her bra about four months ago. Her periods, previously every 29 days, have come every 40 to 60 days for eight months. She has felt tired for most of a year, has gained about 4 kilograms without changing her diet, feels cold when coworkers do not and has become constipated. She takes no prescription medicines, has no nipple piercing or chest surgery, and has never been pregnant. An urgent care visit for the discharge produced a prolactin result of 58 ng/mL, with a laboratory upper limit of 25, and a recommendation to get a brain MRI.

On examination her weight is 68 kilograms and her heart rate is 58. Her skin is dry, and the thyroid is diffusely enlarged and firm without nodules. Gentle pressure produces a milky fluid from several ducts on both sides; it is not bloody. Visual fields are full to confrontation. A urine pregnancy test is negative.

What a Raised Prolactin Can Mean

Prolactin is released by the pituitary and normally held in check by dopamine from the hypothalamus. A raised level is a finding, not a diagnosis. The Endocrine Society guideline lists the causes to exclude before attributing a high prolactin to a pituitary adenoma: pregnancy, medications, hypothyroidism, kidney failure and lesions that compress the pituitary stalk (Melmed et al., 2011). Each of these is common enough to test before imaging.

Testing the Causes in Order

Pregnancy. The commonest cause of high prolactin in a woman of reproductive age. Her pregnancy test is negative.

Medications. Antipsychotics, metoclopramide, some antidepressants, opioids and verapamil can all raise prolactin. She takes none.

Chest wall stimulation. Piercings, shingles, surgery or frequent breast examination can raise prolactin through nerve signals. None apply.

Kidney disease. Reduced clearance raises prolactin. Her creatinine is 0.7 mg/dL, normal.

Hypothyroidism. In primary hypothyroidism the hypothalamus releases more thyrotropin-releasing hormone, which stimulates both thyroid-stimulating hormone and prolactin. Her fatigue, weight gain, cold intolerance, constipation, slow pulse, dry skin and enlarged firm thyroid all point here. Her thyroid-stimulating hormone (TSH) is 38 mIU/L and free thyroxine 0.5 ng/dL, both clearly abnormal. Thyroid peroxidase antibodies are strongly positive, consistent with Hashimoto thyroiditis.

One blood test that the urgent care clinic never ordered explains the milk, the cycles and the fatigue.

Why the MRI Should Wait

A pituitary MRI is not wrong in principle, but ordering it first creates two problems in her case. First, long-standing primary hypothyroidism can enlarge the pituitary itself, because the cells that make TSH multiply under constant stimulation. On imaging this hyperplasia can look like an adenoma and lead to a mistaken diagnosis or even unnecessary surgery (Vilar et al., 2019). Second, small incidental pituitary findings are common in healthy adults, and finding one would add worry without changing her care.

Her prolactin level also fits better with hypothyroidism than with a sizable tumor. Levels below about 100 ng/mL are common with secondary causes, while large prolactin-secreting adenomas typically produce much higher values (Melmed et al., 2011). A small adenoma remains possible, which is why the plan includes a firm decision point for imaging later.

The One Test Not Ordered

Macroprolactin is a large, mostly inactive form of prolactin that some laboratories measure as ordinary prolactin, producing a high result without disease. Vilar et al. (2019) recommend screening for it mainly in patients with a high prolactin and no symptoms. Ms. Haverford has galactorrhea and irregular cycles, which are real effects of active prolactin, so macroprolactin testing would not change the plan now. It would be considered if her prolactin stays high without symptoms after treatment.

Talking With Her About the Result

Ms. Haverford arrived convinced she had a brain tumor, and the visit had to address that fear before any plan would make sense to her. The clinician explained that prolactin is the hormone that makes milk, that many ordinary things raise it, and that her thyroid result offered a clear and common explanation. She was shown her own numbers side by side: a thyroid-stimulating hormone more than eight times the upper limit and a prolactin only about twice it. The clinician also said plainly what was not yet known. A small pituitary adenoma could still be present, and the plan would check for it if the prolactin did not fall. She asked whether she had done something to cause the thyroid problem; she was told that Hashimoto thyroiditis is an autoimmune condition, common in women her age and often running in families, and that her sister and mother might ask their own clinicians about testing if they had symptoms.

Diagnosis

Primary hypothyroidism due to Hashimoto thyroiditis, with secondary hyperprolactinemia causing galactorrhea and oligomenorrhea.

Treatment

Guidelines for hypothyroidism support starting full replacement in young, healthy adults without heart disease, at about 1.6 micrograms of levothyroxine per kilogram of body weight daily (Jonklaas et al., 2014). At 68 kilograms that is about 109 micrograms, so she starts 112 micrograms every morning with water, at least half an hour before eating, and four hours apart from calcium, iron or a multivitamin.

She is told that energy usually improves within weeks, that the nipple discharge should lessen as the thyroid level corrects and that her cycles often return to normal within a few months. Because she may want a pregnancy in the next two years, she is told that thyroid levels need to be well controlled before conception and that her dose will rise in pregnancy, so she should call as soon as a pregnancy test is positive.

Follow-Up and Decision Points

TSH and free thyroxine are repeated in six weeks, with the dose adjusted toward a TSH in the reference range. Prolactin is repeated once she is euthyroid, about three months after starting treatment. Three outcomes are planned for. If prolactin is normal and the discharge has stopped, no imaging is needed. If prolactin remains high despite a normal TSH, a pituitary MRI is ordered and she is referred to endocrinology. If at any point she develops headaches, visual changes or worsening discharge, imaging is done sooner.

Conclusion

The urgent care label was a possibility, not a diagnosis. Testing the causes of a raised prolactin in the order the guideline sets found a simpler explanation, an underactive thyroid, that accounted for every symptom she reported. Treating it first, with a defined point for imaging if prolactin does not settle, protects her from both a missed tumor and an unnecessary one.

References

Jonklaas, J., Bianco, A. C., Bauer, A. J., Burman, K. D., Cappola, A. R., Celi, F. S., Cooper, D. S., Kim, B. W., Peeters, R. P., Rosenthal, M. S., & Sawka, A. M. (2014). Guidelines for the treatment of hypothyroidism. Thyroid, 24(12), 1670-1751. https://doi.org/10.1089/thy.2014.0028

Melmed, S., Casanueva, F. F., Hoffman, A. R., Kleinberg, D. L., Montori, V. M., Schlechte, J. A., & Wass, J. A. H. (2011). Diagnosis and treatment of hyperprolactinemia: An Endocrine Society clinical practice guideline. The Journal of Clinical Endocrinology & Metabolism, 96(2), 273-288. https://doi.org/10.1210/jc.2010-1692

Vilar, L., Vilar, C. F., Lyra, R., & Freitas, M. C. (2019). Pitfalls in the diagnostic evaluation of hyperprolactinemia. Neuroendocrinology, 109(1), 7-19. https://doi.org/10.1159/000499694