Endocrino Flashcards
(11 cards)
A 42-year-old man comes to the physician for a follow-up examination. His blood pressure was 146/91 mm Hg at his appointment 1 month ago; subsequent home blood pressure measurements have ranged from 135/83 mm Hg to 156/96 mm Hg. His blood pressure today is 141/85 mm Hg. Physical examination shows no abnormalities. Pharmacotherapy with lisinopril is initiated. Administration of this drug is most likely to result in decreased activity of which of the following sections of a normal adrenal gland?
The zona glomerulosa of the adrenal cortex is the outermost layer of adrenal parenchyma and lies directly beneath the adrenal capsule (A). The cells of the zona glomerulosa are stimulated by angiotensin II to produce mineralocorticoids, most importantly aldosterone. Inhibition of ACE by lisinopril leads to decreased availability of angiotensin II, in turn resulting in decreased activity of the zona glomerulosa. The response of the zona glomerulosa to angiotensin II is attenuated by low serum potassium or high serum sodium levels.
This patient presents with classic features of hypercalcemia such as fatigue, hypertension, polyuria (“thrones”), abdominal and lower back pain (“groans, bones”), costovertebral angle tenderness (renal “stones”), constipation, and depression (“psychiatric overtones”).
This patient presents with classic features of hypercalcemia such as fatigue, hypertension, polyuria (“thrones”), abdominal and lower back pain (“groans, bones”), costovertebral angle tenderness (renal “stones”), constipation, and depression (“psychiatric overtones”).
Parathyroid chief cells are the site of parathyroid hormone (PTH) production and secretion. Under physiological conditions, parathyroid chief cells maintain calcium homeostasis through PTH-mediated increases in bone resorption, renal calcium absorption, and phosphate excretion. This patient’s hypercalcemia is most likely caused by excessive production and secretion of parathyroid hormone (primary hyperparathyroidism). The most common causes of primary hyperparathyroidism include parathyroid adenoma (approx. 80% of cases) and hyperplasia (approx. 15% of cases).
An increased serum C-peptide concentration and ultrasound findings of polyhydramnios and macrosomia suggest a diagnosis of gestational diabetes. Hyperglycemia causes osmotic diuresis, which leads to increased urinary frequency. Which of the following hormones is predominantly responsible for the observed laboratory changes in this patient?
Human placental lactogen causes pancreatic beta-cell hyperplasia and leads to an increase in insulin (and C-peptide) secretion as well as maternal insulin resistance. This ensures adequate glucose availability for the fetus. If maternal pancreatic function does not overcome insulin resistance, patients can develop gestational diabetes. In response to increased serum glucose concentrations, fetal production of insulin increases, which leads to increased fetal growth (macrosomia) as seen in this case.
A 26-year-old primigravid woman at 25 weeks’ gestation comes to the physician for a prenatal visit. She has no history of serious illness and her only medication is a daily prenatal vitamin. A 1-hour 50-g glucose challenge shows a glucose concentration of 167 mg/dL (N < 135). A 100-g oral glucose tolerance test shows glucose concentrations of 213 mg/dL (N < 180) and 165 mg/dL (N < 140) at 1 and 3 hours, respectively. If she does not receive adequate treatment for her condition, which of the following complications is her infant at greatest risk of developing?
Hyperplasia of islet cells, the pancreatic cells responsible for producing insulin, can occur in utero in response to elevated maternal blood glucose levels, e.g., due to gestational diabetes. This can cause infantile hyperinsulinemia and put the infant at risk for hypoglycemia once the maternal placental transfer of glucose ceases after birth.
A 15-year-old girl comes to the physician because of a 2-month history of progressive fatigue and weakness. She also reports recurrent headaches for 2 years, which have increased in severity and frequency. Her blood pressure is 185/95 mm Hg. Serum studies show a morning renin activity of 130 ng/mL per hour (N=1–4), a morning aldosterone concentration of 60 ng/dL (N=5-30), and a potassium concentration of 2.9 mEq/L. Further evaluation is most likely to show which of the following?
The presence of pleomorphic smooth muscle cells in the renal cortex in combination with elevated renin and aldosterone concentrations is highly indicative of a juxtaglomerular tumor. Excessive renin production by these tumor cells stimulates aldosterone release. Consequently, patients exhibit symptoms of secondary hyperaldosteronism.
A 55-year-old woman with type 2 diabetes mellitus comes to the physician for evaluation of worsening tingling of her feet at night for the last 6 months. Two years ago, she underwent retinal laser photocoagulation in both eyes. She admits to not adhering to her insulin regimen. Her blood pressure is 130/85 mm Hg while sitting and 118/70 mm Hg while standing. Examination shows decreased sense of vibration and proprioception in her toes and ankles bilaterally. Her serum hemoglobin A1C is 11%. Urine dipstick shows 2+ protein. Which of the following additional findings is most likely in this patient?
Genitourinary manifestations of diabetic autonomic neuropathy include incomplete bladder emptying, urinary retention, erectile dysfunction, retrograde ejaculation, and dyspareunia. The loss of afferent and efferent autonomic innervation of the bladder results in the inability to sense a full bladder and incomplete emptying, predisposing patients to overflow incontinence and recurrent UTI.
A 36-year-old woman comes to the physician because of a 3-month history of a painless lump on her neck. She says that the lump has gradually increased in size and is hard to the touch. Family history is unremarkable. She appears healthy. Examination shows a 2.5-cm (1-in) firm, irregular swelling on the left side of the neck that moves with swallowing. There is painless cervical lymphadenopathy. Ultrasound of the neck shows a solitary left lobe thyroid mass with increased vascularity and hyperechogenic punctate regions. A fine-needle aspiration biopsy is scheduled for the upcoming week. Which of the following is the most likely diagnosis?
Papillary thyroid carcinomas are the most common type of thyroid cancer (∼ 80% of cases) and have a peak incidence between 30–50 years of age. These carcinomas commonly manifest with early lymphatic spread. Patients often present with painless cervical lymphadenopathy that may be detectable before the primary tumor. The hyperechogenic punctate regions seen on this patient’s ultrasound likely represent microcalcifications, another characteristic feature of this type of thyroid cancer. Based on the overall incidence rate, affected age group, and metastatic pattern, papillary thyroid carcinoma is the most likely diagnosis in this patient.
A 40-year-old woman comes to the physician because of a small lump on the right side of her neck that she noticed while putting lotion on 1 week ago. She has not had any weight change, palpitations, or altered bowel habits. There is no family history of serious illness. Menses occur at regular 30-day intervals and last for 4 days. She appears well. Her temperature is 37.0°C (98.6° F), pulse is 88/min, and blood pressure is 116/74 mm Hg. Examination shows a small nodule on the right side of the neck that moves with swallowing. There is no lymphadenopathy. The lungs are clear to auscultation. The remainder of the examination shows no abnormalities. Ultrasound of the neck shows a 0.9-cm (0.35-in) right lobe thyroid mass with microcalcifications and irregular margins. Which of the following is most likely to be helpful in determining the next step in management?
Measurement of thyroid-stimulating hormone (TSH) serum concentration and thyroid ultrasound should be performed in all patients with a suspected thyroid nodule to determine further management. If TSH levels are normal or elevated, this patient should undergo regular monitoring in case the tumor grows to ≥ 1 cm, in which case fine-needle aspiration biopsy would be indicated because of her suspicious ultrasound findings (i.e., a mass with microcalcifications and irregular margins). If TSH levels are subnormal, she should be evaluated for hyperthyroidism with thyroid scintigraphy.
________________ and uniform follicles are characteristic histopathologic findings of follicular thyroid cancer, the second most common type of thyroid cancer after papillary thyroid cancer. Follicular thyroid cancer is characterized by hematogenous spread (most commonly to the lungs and bones) and lymph node involvement is rare.
Further treatment in this patient will likely involve total thyroidectomy, possibly followed by radioiodine therapy. Afterward, thyroid hormone replacement therapy (i.e., levothyroxine) in the highest possible dose (according to the patient’s tolerance) will be initiated to suppress TSH and thus reduce the risk of stimulating remaining malignant tissue.
Capsular and blood vessel invasion
A 36-year-old woman comes to the physician for a follow-up visit after she had a PET scan that showed a nodule on the thyroid gland. She has no difficulty or pain while swallowing. She was treated for non-Hodgkin lymphoma at 28 years of age, which included external beam radiation to the head and neck and four cycles of chemotherapy. She appears healthy. Vital signs are within normal limits. Physical examination shows no abnormalities. Serum studies show:
Glucose 82 mg/dL
Creatinine 0.7 mg/dL
Thyroid-stimulating hormone 3 μU/mL
Ultrasound of the neck shows a 1.2-cm (0.5-in) nodule on the left lobe of the thyroid with irregular margins and microcalcifications. A fine-needle aspiration biopsy shows Psammoma bodies and cells with clear, ground-glass, empty nuclei. Which of the following is the most appropriate next step in management?
Total thyroidectomy is an effective treatment option for most thyroid cancers, including well-differentiated thyroid carcinomas such as papillary carcinoma. Papillary thyroid cancer is more common in women than men, and prior exposure to radiation (particularly during childhood) is an environmental risk factor. Small papillary microcarcinomas (< 1.0 cm, no affected lymph nodes, no metastases) can be treated with a partial resection (hemithyroidectomy). This patient’s history of external beam radiation to the head and neck region is a contraindication for hemithyroidectomy because of the risk of recurrence in the contralateral thyroid lobe.
Neck dissection should be considered for advanced papillary carcinoma with extrathyroidal spread, even when there is no clinical suspicion of nodal metastasis.
