Endocrine case studies

Published on 02/03/2015 by admin

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Last modified 02/03/2015

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Endocrine case studies

1. A 34-year-old woman has new-onset hypertension. Her serum potassium level is 2.7 mmol/L. Initial hormone screening shows a plasma aldosterone (PA) of 55 ng/dL (normal [nl], 1–16) and a plasma renin (PR) of 0.1 ng/mL/hour (nl, 0.15–2.33). What is the probable diagnosis?

The presence of hypertension and hypokalemia suggests primary aldosteronism (Conn syndrome). The PA level is elevated, the PR is suppressed, and the PA/PR ratio is greater than 20, supporting this diagnosis. The diagnosis can be confirmed by demonstrating the failure of PA to suppress after volume expansion with intravenous saline or oral salt loading. The next step is to establish whether the cause is an aldosterone-producing adenoma or bilateral adrenal hyperplasia. Abdominal computed tomography (CT) should be performed. Because of her young age and very low serum potassium level, an aldosterone-producing adrenal adenoma is the most likely cause. The treatment for an aldosterone-producing adrenal adenoma is surgery. Spironolactone should be given to control blood pressure and to normalize the serum potassium preoperatively (see Chapter 27).

2. A 32-year-old business executive develops amenorrhea. She has not recently lost weight but states that her job is very stressful. Evaluation reveals the following laboratory results: serum estradiol = 14 pg/mL (nl, 23–145), luteinizing hormone (LH) = 1.2 mIU/mL (nl, 2–15), follicle-stimulating hormone (FSH) = 1.5 mIU/mL (nl, 2–20), prolactin = 6.2 ng/mL (nl, 2–25), thyroid-stimulating hormone (TSH) = 1.2 mU/L (nl, 0.5–5.0), and a serum pregnancy test is negative. A magnetic resonance imaging (MRI) scan of her pituitary gland is normal. What is the probable diagnosis?

3. A nulliparous 48-year-old woman presents with symptoms of thyrotoxicosis. She has a modest, nontender goiter and no exophthalmos. She takes no medications and has had no recent radiology procedures. The following results are found on thyroid evaluation: free thyroxine (T4) = 3.5 ng/dL (nl, 0.8–1.8), TSH less than 0.1 mU/L, 24-hour radioactive iodine uptake (RAIU) = 1% (nl, 20%–35%), thyroglobulin = 35 ng/mL (nl, 2–20), and sedimentation rate = 10 mm/hour. What is the likely diagnosis?

The patient has clinical and biochemical thyrotoxicosis, but the RAIU is low. The differential diagnosis includes postpartum thyroiditis, silent thyroiditis, subacute thyroiditis, factitious thyrotoxicosis, and iodine-induced thyrotoxicosis. She has never been pregnant and denies medication use and recent iodine exposure. The nontender gland, elevated thyroglobulin, and normal sedimentation rate are most consistent with silent thyroiditis. A transient (1–3 months) thyrotoxic phase followed by a transient (1–3 months) hypothyroid phase is expected before the condition resolves; 20% of patients, however, remain hypothyroid. If symptomatic, the thyrotoxic phase is best treated with beta-blockers, and the hypothyroid phase can be managed, if necessary, with levothyroxine (see Chapters 33 and 35).

4. A 38-year-old man has coronary artery disease, xanthomas of the Achilles tendons, and the following serum lipid profile: cholesterol = 482 mg/dL, triglyceride (TG) = 125 mg/dL, high-density lipoprotein (HDL) cholesterol = 42 mg/dL, and low-density lipoprotein (LDL) cholesterol = 415 mg/dL. What is the probable diagnosis?

5. A 28-year-old man presents because of infertility. He is found to have small, firm testes and gynecomastia. Laboratory testing shows the following abnormalities: testosterone = 206 ng/dL (nl, 300–1000), LH = 88 mIU/mL (nl, 2–12), and FSH = 95 mIU/mL (nl, 2–12). What is the likely diagnosis?

6. A 38-year-old nurse presents in a stuporous state; the blood glucose level is 14 mg/dL. Additional blood is drawn, and the patient is quickly resuscitated with intravenous glucose. Further testing on the saved serum reveals the following: serum insulin = 45 μU/mL (nl, <22), C-peptide = 4.2 ng/mL (nl, 0.5–2.0), and proinsulin = 7 pmol/L (nl, <5). A sulfonylurea screen is negative. What is the probable diagnosis?

7. A 28-year-old woman develops amenorrhea. She has type 1 diabetes mellitus. Further testing reveals the following serum hormone values: estradiol = 15 pg/mL (nl, 23–145), LH = 78 mIU/mL (nl, 2–15), FSH = 92 mIU/mL (nl, 2–20), prolactin = 12 ng/mL (nl, 2–25), TSH = 1.1 mU/L; a pregnancy test is negative. What is the most likely diagnosis?

8. A 34-year-old woman presents with galactorrhea, amenorrhea, headaches, fatigue, and weight gain. Laboratory evaluation reveals the following: prolactin = 58 ng/mL (nl, 2–25), free T4 = 0.2 ng/dL (nl, 0.8–1.8), and TSH greater than 60 mU/L (nl, 0.5–5.0). She has an enlarged pituitary gland on MRI scan. What is the probable diagnosis?

9. A 6-year-old girl has recently developed breast enlargement and some pubic hair. She has not complained of headaches and has had good health otherwise. Her older sister entered puberty at approximately 8 years of age. Her height is at the 90th percentile for her age, and her physical examination reveals Tanner stage III breast development and stage II pubic hair growth. Abdominal and pelvic examinations are normal. Laboratory tests show the following results: LH = 7 mIU/mL (nl, 2–15), FSH = 8 mIU/mL (nl, 2–20), prolactin = 6 ng/mL (nl, 2–25), TSH = 1.9 mU/L (nl, 0.5–5.0), and a normal pituitary MRI scan. Her bone age is 1.8 years ahead of the chronologic age. What is the probable diagnosis?

10. A 19-year-old man presents with excessive thirst and urination. Laboratory evaluation shows the following: serum glucose = 88 mg/dL, serum sodium = 146 mmol/L, serum osmolality = 298 mOsm/kg, and urine volume = 8800 mL/24 hour. A water deprivation test is performed, and it shows a urine osmolality of 90 mOsm/kg with no response to water deprivation and an increase in urine osmolality to 180 mOsm/kg after the administration of vasopressin. What is the likely diagnosis?

11. A 25-year-old woman presents with a cushingoid appearance. The results of hormone testing are as follows: 24-hour urine cortisol = 318 μg (nl, 20–90), morning serum cortisol = 28 μg/dL (nl, 5–25), and morning plasma adrenocorticotropic hormone (ACTH) = 65 pg/mL (nl, 10–80). After an 8-mg oral bedtime dose of dexamethasone, the morning serum cortisol = 3 μg/dL. What is the probable diagnosis?

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