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.
A 34-year-old woman comes to the physician because she has not had her menses for 6 months. She has also had milky-white discharge from her nipples, frequent headaches, and blurry vision during the past 4 months. Menses had previously occurred at regular 30-day intervals and lasted for 4–5 days with moderate flow. She takes no medications. She has two children who are healthy and attend middle school. She is 163 cm (5 ft 4 in) tall and weighs 68 kg (145 lb); BMI is 26 kg/m2. Vital signs are within normal limits. Cardiopulmonary examination shows no abnormalities. Pelvic examination shows vaginal atrophy and a normal uterus. Neurologic examination shows no focal findings. A complete blood count and serum concentrations of electrolytes, creatinine, and glucose are within the reference range. A urine pregnancy test is negative. Serum studies are most likely to show which of the following sets of findings in this patient?
Prolactinomas are the most common cause of hyperprolactinemia. Hyperprolactinemia has an inhibitory effect on GnRH (gonadotropin-releasing hormone), which leads to a decrease in LH and FSH (luteinizing hormone and follicle-stimulating hormone) and subsequently a decline in estrogen and testosterone, resulting in amenorrhea/oligomenorrhea, vaginal atrophy, and endometrial atrophy. Hyperprolactinemia has a direct tropic effect on breast tissue and triggers lactation, explaining this patient’s galactorrhea — a finding that is seen in 80% of premenopausal women with hyperprolactinemia. A pituitary tumor of any kind can cause compressive symptoms, leading to bitemporal hemianopsia and/or palsy of the adjacent cranial nerves III, IV, or VI. The best next step in the diagnosis of suspected pituitary adenoma is a brain MRI with contrast. First-line treatment for prolactinomas is dopamine agonists (e.g., cabergoline), which inhibit prolactin secretion and induce shrinkage of the tumor.
A 40-year-old man comes to the physician for the evaluation of episodic headaches for 5 months. The headaches involve both temples and are 4/10 in intensity. The patient has been taking acetaminophen, but the headaches did not subside. He has also had visual disturbances, including double vision. He has no nausea, temperature intolerance, or weight changes. The patient does not smoke. He drinks 2–3 beers on weekends. He appears pale. His temperature is 37°C (98.6°F), pulse is 75/min, and blood pressure 125/80 mm Hg. Ophthalmologic examination shows impaired peripheral vision bilaterally. An MRI scan of the head with contrast shows a 16 × 11 × 9 mm intrasellar mass. Further evaluation is most likely to show which of the following findings?
This patient has a pituitary adenoma, the most common form of which is a prolactinoma that can cause hyperprolactinemia. Hyperprolactinemia results in hypogonadotropic hypogonadism because prolactin inhibits the synthesis and release of gonadotropin-releasing hormone (GnRH), which results in decreased secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In men, decreased concentrations of LH result in decreased production of testosterone in testicular Leydig cells. The resulting manifestations include erectile dysfunction, decreased libido, reduced testicular volume, infertility, gynecomastia, and loss of axillary hair. The visual deficits caused by a growing pituitary adenoma develop very gradually as the mass grows and compresses the optic chiasm (causing bitemporal hemianopia) and the oculomotor nerve (causing diplopia).
This patient’s neck swelling and elevated calcitonin suggest a diagnosis of medullary thyroid cancer. This, in combination with a condition that causes the triad of palpitations, sweating, and headaches, is consistent with multiple endocrine neoplasia type 2 (MEN 2). Which of the following laboratory abnormalities is most likely to be seen?
Plasma metanephrines (normetanephrine and metanephrine) are a sensitive indicator of pheochromocytoma, which is characterized by intermittent hypertension, diaphoresis, headaches, and palpitations, all of which are seen in this patient. This condition is associated with the MEN 2 syndromes and about 50% of patients with MEN 2A or MEN 2B develop pheochromocytoma in addition to medullary thyroid cancer. 24-hour urinary metanephrines and catecholamines should be measured to confirm the diagnosis. Other diagnostic tests include abdominal imaging to look for an adrenal mass or genetic testing for MEN 2A or MEN 2B.
Increased metanephrines may also be seen in the case of ganglioneuromas and neuroblastomas, which can be part of MEN 2B syndrome.
A 33-year-old man comes to the emergency department because of a pounding headache for the past 3 hours. The pain is 8 out of 10 in intensity, does not radiate, and is not relieved by ibuprofen. He also has associated dizziness, blurring of vision, and palpitations. He has had similar episodes over the last 6 months but none this severe. He has not had fever, weight change, or loss of appetite. He underwent an appendectomy at the age of 18. His father died of renal cancer. He is diaphoretic. His temperature is 36.8°C (98.4°F), pulse is 112/min, and blood pressure is 220/130 mm Hg. Physical examination shows no abnormalities. Laboratory studies show:
Hemoglobin 14.8 g/dL
Leukocyte count 9600/mm3
Platelet count 345,000/mm3
Serum
Glucose 99 mg/dL
Na+ 137 mEq/L
K+ 4.2 mEq/L
Cl- 105 mEq/L
Creatinine 1.0 mg/dL
Urine dipstick shows no abnormalities. Which of the following findings on imaging is the most likely explanation for this patient’s symptoms?
Pheochromocytoma is most commonly an adrenal medullary mass and manifests with episodic bouts of hypertension, diaphoresis, headaches, tachycardia, and palpitations, as seen in this patient. Pheochromocytomas cause an increase in catecholamines and metanephrines, which can be detected with plasma or urine testing
A 30-year-old man comes to the physician after receiving a high blood pressure reading of 160/90 mm Hg at an annual employee health check-up. During the past few months, the patient has had occasional headaches and mild abdominal pain, both of which were relieved with ibuprofen. He has also had several episodes of heart palpitations. He has no history of serious illness. His mother and father both have hypertension. He has smoked one pack of cigarettes daily for the past 10 years and drinks one glass of wine daily. He occasionally smokes marijuana. He appears pale. His temperature is 36.8°C (98.2°F), pulse is 103/min, and blood pressure is 164/102 mm Hg. Physical examination shows no abnormalities. Laboratory studies show:
Hemoglobin 15.3 g/dL
Leukocyte count 7900/mm3
Platelet count 223,000/mm3
Serum
Na+ 138 mEq/L
K+ 4.6 mEq/L
Cl- 103 mEq/L
Urea nitrogen 14 mg/dL
Glucose 90 mg/dL
Creatinine 0.9 mg/dL
Plasma metanephrines 1.2 nmol/L (N < 0.5)
Urine toxicology screening is positive for tetrahydrocannabinol (THC). Renal doppler shows no abnormalities. A CT scan of the abdomen shows a mass in the left adrenal gland. Which of the following is the most appropriate next step in management?
Phenoxybenzamine therapy
74%
Phenoxybenzamine inhibits the effect of catecholamines on alpha receptors and thereby lowers blood pressure and prevents a potential hypertensive crisis. This blood pressure management is especially important before surgery because manipulation of the tumor tissue during its removal may cause high amounts of catecholamines to release into the bloodstream. It is important to administer alpha blockers before beta blockers because beta blockers inhibit the vasodilatory effect of peripheral β2-adrenoceptors. Therefore, beta blockers alone would lead to unopposed α-adrenoceptor stimulation, which causes further vasoconstriction and potentially a hypertensive crisis as a result of ectopic catecholamine release. After sufficient α-adrenergic blockade, a beta blocker may be started for additional control of blood pressure and tachyarrhythmias, followed by laparoscopic tumor resection (adrenalectomy).
A 40-year-old woman comes to the physician because of a 3-month history of a lump on her neck. The lump is mildly painful. She appears healthy. Examination shows a swelling on the left side of her neck that moves on swallowing. Cardiopulmonary examination shows no abnormalities. Her TSH is 3.6 μU/mL. Ultrasound shows a 0.4-cm (0.15-in) hypoechoic mass in the left thyroid lobe. Fine-needle aspiration of the mass shows neoplastic follicular cells. Molecular analysis of the aspirate shows a mutation in the RAS gene. Which of the following is the most appropriate next step in management?
Thyroid lobectomy (hemithyroidectomy) is the preferred treatment for patients with well-differentiated intrathyroidal cancers < 1 cm without nodal or distant metastasis or high-risk features (patient age > 45 years, family history of cancer, and history of head or neck radiation). In these patients, hemithyroidectomy allows for definitive diagnosis (via histological analysis showing invasion of the basement membrane) and definitive management with a high probability of cure. Preservation of the contralateral lobe decreases the need for thyroid hormone replacement therapy and mitigates surgical risks associated with thyroidectomy (e.g., hypoparathyroidism).
In patients with intrathyroidal tumors > 4 cm, extrathyroidal spread, metastasis, or high-risk features, hemithyroidectomy is contraindicated and total thyroidectomy should be performed.
A 36-year-old woman comes to the gynecologist because of a 4-month history of irregular menstrual cycles. Menses occur at irregular 15 to 45-day intervals and last 1–2 days with minimal flow. She also reports a milk-like discharge from her nipples for 3 months, accompanied by fatigue and muscle and joint pain. She does not have abdominal pain, fever, or headache. She has recently gained 2.5 kg (5.5 lb) of weight. She was diagnosed with schizophrenia and started on aripiprazole by a psychiatrist 8 months ago. She has hypothyroidism but has not been taking levothyroxine for 6 months. She does not smoke or consume alcohol. She appears healthy and anxious. Her vital signs are within normal limits. Pelvic examination shows vaginal atrophy. Visual field and skin examination are normal. Laboratory studies show:
Hemoglobin 12.7 g/dL
Serum
Glucose 88 mg/dL
Creatinine 0.7 mg/dL
Thyroid-stimulating hormone (TSH) 16.3 μU/mL
Cortisol (8 AM) 18 μg/dL
Prolactin 88 ng/mL
Urinalysis is normal. An x-ray of the chest and ultrasound of the pelvis show no abnormalities. Which of the following is the most likely explanation for the nipple discharge in this patient?
Increased TSH in a hypothyroid patient (e.g., fatigue, recent weight gain, and myalgia) who has not been taking their levothyroxine medication suggests primary hypothyroidism. In primary hypothyroidism, decreased T3 and T4 levels stimulate the secretion of thyrotropin-releasing hormone (TRH) by the hypothalamus, which in turn increases TSH release by the anterior pituitary. In addition to increasing TSH production, excessive TRH also stimulates the lactotroph cells of the anterior pituitary to release prolactin, thus resulting in a state of hyperprolactinemia.
This patient has primary hyperparathyroidism, which can cause abdominal pain, depressed mood, kidney stones, and increased calcium and parathyroid hormone concentrations. This condition, in combination with young age at presentation and a family history of thyroid cancer, raises suspicion for an underlying diagnosis of multiple endocrine neoplasia type 2A (MEN 2A), which is confirmed by the detection of a mutation of the RET gene. Which of the following is the most appropriate next step in management?
Increased metanephrine concentrations in the urine or plasma are indicative of pheochromocytoma, a catecholamine-secreting neuroendocrine tumor associated with MEN 2 syndromes. Pheochromocytomas usually cause paroxysms of elevated blood pressure and heart rate, but normal vitals on examination do not rule out this condition. For patients in whom a diagnosis of MEN 2 is suspected or confirmed, it is critical to evaluate for pheochromocytoma before undergoing surgical procedures (e.g., parathyroidectomy for the management of primary hyperparathyroidism or thyroidectomy to prevent the development of medullary thyroid cancer). Intraoperative catecholamine release from a pheochromocytoma can otherwise result in hemodynamic instability during the procedure.
This patient presents with features of hypoaldosteronism (hyponatremia, hyperkalemia, hypotension), hypoandrogenism (loss of pubic hair), and hypocortisolism (lethargy, hypotension, low cortisol, elevated ACTH). Deficiency in all three hormone classes of the adrenal cortex should raise concern for primary adrenal insufficiency (i.e., Addison disease). CT scan of the abdomen with contrast shows bilateral adrenal enlargement. Which of the following is the most likely cause of this patient’s findings?
Constitutional symptoms and long-standing productive cough in someone who has migrated from a country with a high TB burden (e.g., the Philippines) should raise suspicion for tuberculosis (TB), which is caused by infection with the acid-fast bacillus Mycobacteria tuberculosis. TB can affect any organ, including the adrenal glands causing infectious adrenalitis, which may result in symptoms of chronic primary adrenal insufficiency and bilateral adrenal enlargement. Further management of this patient should include confirmation of TB with sputum microscopy and PCR, initiation of the appropriate TB treatment, and replacement of the deficient glucocorticoids and mineralocorticoids.
Normally, hypoglycemia is expected in patients with primary adrenocortical insufficiency because of the lack of glucocorticoid-mediated diabetogenic effects. However, this patient is diabetic and glucose control is likely hindered by the current infection.
A 43-year-old woman comes to the physician for an annual health maintenance examination. She has had excessive fatigue for the last month. A few weeks ago, she was diagnosed with carpal tunnel syndrome for which she received a padded cast. She has mild persistent asthma and anxiety disorder. She is sexually active with her husband of 19 years. Menses occur at regular 28-day intervals and last 4–6 days. Her last menstrual period was 2 weeks ago. She works a desk job in accounting and has recently been working long hours due to an upcoming company merger. Her father has a history of a brain tumor. Current medications include alprazolam and a fluticasone-formoterol inhaler. She drinks 2–3 glasses of red wine per night and has smoked one pack of cigarettes daily for 16 years. She is 160 cm (5 ft 3 in) tall and weighs 81.6 kg (180 lb); her BMI is 32 kg/m2. Her temperature is 37.2°C (99.0°F), pulse is 92/min, and blood pressure is 128/80 mm Hg. Examination shows no abnormalities. Fasting laboratory studies show:
Hemoglobin 13 g/dL
Serum
Na+ 137 mEq/L
K+ 4.6 mEq/L
Cl- 105 mEq/L
HCO3- 22 mEq/L
Urea nitrogen 17 mg/dL
Glucose 160 mg/dL
Creatinine 0.9 mg/dL
Which of the following is the most likely underlying mechanism of this patient’s hyperglycemia?
Insulin resistance and subsequent pancreatic β-cell dysfunction are the major pathophysiological mechanisms of type 2 diabetes mellitus. This patient meets the criteria for obesity, a cardinal risk factor for type 2 diabetes mellitus. A fasting glucose level of ≥ 126 mg/dL is diagnostic of diabetes mellitus.
Obesity with increased plasma levels of free fatty acids impairs insulin-dependent glucose uptake into myocytes and adipocytes, resulting in hyperglycemia. The absence of insulin-dependent inhibition of hepatic glycogenolysis and gluconeogenesis further promotes hyperglycemia. Initially, insulin resistance is compensated by increased insulin secretion. Over the course of the disease, pancreatic β-cell production capacity declines, and diabetes mellitus manifests as fasting hyperglycemia.
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Anato Mnemotecnias4
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Fisio Mnemotecnias2
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Musculoesquelético26
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Comportamiento20
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Bioestadística24
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Embarazo30
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Neurología25
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Inmunología26
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Ciencias Fundamentales10
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Sangre28
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S. Reproductivo Mujer25
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S. Reproductivo Hombre30
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Endocrino20
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Respiratorio25
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Cardiología34
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Renal25
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Gastrointestinal25
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Piel20
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Multisistemico20
