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Select the ONE answer that is BEST in each case.
A 62-year-old man is seen in the office. Routine blood testing reveals elevated LDL cholesterol. Which of the following is the most likely cause for the elevated LDL?
In Western societies, most dyslipidemias are secondary. The most common predisposing cause is diet, and the second common is DM. Hypothyroidism, renal disease, alcoholism, and anorexia nervosa are also associated with secondary dyslipidemias. Many drugs (e.g., estrogen, glucocorticoids) can also cause secondary dyslipidemias.
Which of the following dietary abnormalities is most commonly associated with elevated cholesterol levels?
The most important factors in diet-induced cholesterol elevation are the amount of total fat and saturated fat consumed. Cholesterol intake is next in importance. Obesity and caloric excess usually result in high triglyceride levels.
A 63-year-old asymptomatic woman is investigated for a high alkaline phosphatase (ALP) level. X-rays of the pelvis show multiple porotic and sclerotic lesions with characteristic whorls of trabeculation. Her excretion of urinary hydroxyproline is also elevated. Which of the following is the most likely diagnosis?
The elevated ALP and hydroxyproline are diagnostic for Paget’s disease. The bony lesions are blastic and the sacrum and pelvis are most frequently involved, followed closely by the tibia and femur. Hypercalcemia can complicate immobilization. The etiology is unknown, but a viral agent has been postulated. Symptoms may be absent or severe (pain, deformity). In metastatic cancers of most types the lesion are lytic, and the other metabolic abnormalities do not have an elevation in hydroxyproline.
A 20-year-old man develops symptoms of weakness with numbness and tingling in his hands. The physical examination is normal, but his calcium is 7.4 mg/dL (8.4–10.2 mg/dL). Which of the following additional serum values is most consistent with the diagnosis of vitamin D deficiency?
Many affected persons with vitamin D deficiency have no demonstrable abnormality except for hypocalcemia, hypophosphatemia, and increased PTH levels. Decreased calcium absorption, which is vitamin D dependent, results in mild hypocalcemia that leads to the secondary hyperparathyroidism. This in turn results in increased renal phosphate excretion and hypophosphatemia.
A 19-year-old woman develops weight loss, tremor, and heat intolerance. On examination, she has goiter, warm skin, and a fine tremor of her hands. Her TSH is low and her free T4 and T3 are elevated. Which of the following cardiac findings is most likely to occur in her?
Atrial fibrillation and cardiomegaly are common cardiac manifestations, but are more common in the elderly. Other symptoms include palpitations, tachycardia, nervousness, sweating, and dyspnea. Sinus tachycardia is the most common cardiac manifestation in a young individual with hyperthyroidism.
A thyroid nodule is found on a 40-year-old woman on routine evaluation. She has no prior history of thyroid disease and clinically feels well. There is a 15-mm nontender nodule on the right lobe of the thyroid with no associated lymphadenopathy. Thyroid function tests are normal. Which of the following is the most appropriate next step in management?
Needle biopsy can be used in numerous diseases, but the main rationale is to differentiate benign from malignant nodules. A thyroid scan is appropriate if the TSH is suppressed suggesting a possible “hot” nodule (hyperfunctioning nodules are very rarely malignant). The specimen must be read by an experienced cytologist. It is difficult to diagnose differentiated follicular carcinoma or to differentiate lymphoma from
Which of the following mechanisms is responsible for the release of vasopressin (antidiuretic hormone)?
Regulation of vasopressin is by osmotic and nonosmotic stimuli such as volume and neural stimuli arising outside the hypothalamus. As little as 15% of cells remaining in the posterior hypothalamus are sufficient to prevent permanent DI.
A 40-year-old woman develops light-headed episodes associated with sweating, palpitations, and hunger whenever she misses a meal. Her physical examination is normal, and she is not taking any medications. On one such episode, while in hospital, her blood glucose level was 30 mg/dL and the symptoms resolved with giving her juice. Which of the following is the most likely diagnosis?
Classification of hypoglycemia includes spontaneous causes such as reactive or fasting hypoglycemia and pharmacologic or toxic causes. The diagnosis of insulinoma is most certain when Whipple’s triad is fulfilled: symptoms consistent with hypoglycemia, low plasma glucose, and relief of symptoms with elevation of plasma glucose to normal.
A 63-year-old has newly diagnosed light-chain amyloidosis (AL). In which of the following organs, is deposition of amyloid protein most likely to cause symptoms? (A) heart (B) red cells (C) thyroid (D) pancreas (E) liver
Cardiac failure and arrhythmias frequently occur in cardiac amyloid. The ECG reveals lowvoltage QRS complexes and conduction disturbances. Red cells are not involved, and involvement of the thyroid, liver, and pancreas is usually asymptomatic. The precursors of the AL, amyloid protein found in primary AL and myeloma, are kappa and lambda light chains. Serum amyloid A protein (SAA) is the precursor for the AA amyloid found in secondary AL.
A 25-year-old woman presents with intermittent symptoms of sweating, palpitations, and hunger. During each episode, her glucose level is less than 40 mg/dL. Her insulin level is low and glucagon level is high. Which of the following best describes the hormone function of glucagon?
This person has either fasting or reactive hypoglycemia. Glucagon exerts a marked effect on carbohydrate, fat, and lipid metabolism, and increases cAMP in many tissues. It is the first counterregulatory hormone to respond to hypoglycemia, and it does this by increasing glycogenolysis and gluconeogenesis. Glucagonomas of the pancreas present with features such as mild DM, psychiatric disturbances, diarrhea, venous thromboses, and skin findings (necrolytic migratory erythema).
A 34-year-old woman notices lumps on her elbows and yellow patches below her eyelids. On examination, she has tendon xanthomas on her elbows and xanthelasma under the eyelids. Her lipid profile is consistent with a diagnosis of familial hypercholesterolemia (increased LDL). Which of the following statements regarding the treatment of this condition is correct?
In mild cases, dietary therapy may suffice, but the vast majority of patients require drug therapy. Statins are clearly the most effective medications available, but the majority of patients will not have optimal cholesterol control, even with maximum doses of a statin. Homozygous patients always require combination therapy.
Which of the following is the most common manifestation of multiple endocrine neoplasia, type I (MEN I)?
Primary hyperparathyroidism develops in over 87% of those with MEN I. Polyendocrine adenomatosis, type I, frequently includes islet cell tumors of the pancreas, leading to the Zollinger-Ellison syndrome, insulinomas, and glucagonomas. Inheritance is via an autosomal dominant pattern. Hypercalcemia does not usually occur until after the first decade.
A 51-year-old woman is experiencing irregular periods for the past 6 months as well as symptoms of hot flashes and night sweats. Her physical examination is normal. Hormone replacement therapy (HRT) is prescribed for her symptoms. Which of the following is the most likely additional benefit of HRT?
HRT can reduce osteoporosis related fractures. Estrogens cause thickening of vaginal mucosa and can improve urogenital symptoms, and postmenopausal symptoms. The evidence for protection against CAD and dementia is epidemiologic. Randomized trials have failed to show a reduction in CAD risk with HRT. The risk of venothromboembolism and breast cancer is increased not decreased.
A 37-year-old woman presents with symptoms of fatigue, muscle weakness, and weight gain. She has no past medical history and is not taking any medications. On examination, her blood pressure is 164/92 mm Hg and pulse 84/min. She has multiple skin bruises, facial fullness, and trunkal obesity with red “stretch marks.” Muscle strength in the proximal muscles is 4+/5 and reflexes are normal. Which of the following is the most appropriate initial diagnostic test?
This patient has Cushing’s syndrome. The diagnosis is established by demonstrating increased cortisol secretion (24-hour urine cortisol collection) or by failure to suppress AM cortisol levels after overnight dexamethasone administration. Investigations for either adrenal tumor or pituitary adenoma (with CT or MR) are only considered once the diagnosis of Cushing’s syndrome is established.
A 43-year-old woman develops increased hand and foot size. On examination, she has spadelike hands, coarsened facial features, and a gap between her incisors. Her blood pressure is 155/85 mm Hg and pulse 80/min, cardiac apical beat is sustained with normal heart sounds. Which of the following is the most likely effect of this syndrome on the muscles?
Growth hormone excess in acromegaly produces hypertrophy of muscle. Initially, strength may be increased, but this is transient, and a third of patients will experience weakness, likely secondary to myopathy.
A 7-year-old boy has demineralized bones with pseudofractures. Physiologic doses of vitamin D do not result in improvement. Which of the following is most likely to be associated with this syndrome?
Vitamin D-resistant rickets is a familial disorder, with an X-linked recessive pattern, treated with pharmacologic doses of vitamin D. Half the affected individuals have alopecia, and this tends to correlate with severity. Rickets and osteomalacia are characterized by impaired mineralization of bone. Osteoporosis is a disorder with a diminished amount of normally mineralized bone.
An 18-year-old girl is brought to hospital because of weakness. She feels well, but is under a lot of stress at school. Most of her time is spent studying, dieting, and exercising. She is 5’8”, weighs 78 lb, and appears unwell. Her blood pressure is 85/70 mm Hg, pulse 50/min, and there is muscle wasting. Which of the following is this patient most likely at risk for?
Risk of death in anorexia nervosa is also associated with hypothermia, suicide, or pneumonia with emaciation. Because of the danger of ventricular tachyarrhythmias, patients should be followed with ECGs. A prolonged QT interval is a sign of danger. In addition, severe weight loss can lead to both systolic and diastolic dysfunction of the ventricles.
A 53-year-old man develops severe pain, redness, and swelling in his left big toe. Which of the following conditions is most likely associated with this condition?
In gouty patients, nephrolithiasis and uric acid nephropathy may occur. The association of cardiovascular disease, hypertension, pyelonephritis, and hyperlipoproteinemia with gout contributes to the high prevalence of renal disease in these individuals.
A 27-year-old woman complains of pain in her left shin. X-rays of the leg reveal a stress fracture of the tibia, decreased cortical bone density, and increased radiolucency. She is suspected of having osteomalacia (impaired mineralization of bone matrix). Which of the following is the most common biochemical manifestation of osteomalacia?
Vitamin D levels are decreased in osteomalacia. In severe osteomalacia, there is bowing of the long bones, inward deformity of the long bones, and wide osteoid borders on bone surfaces. Hypocalcemia is characteristic of osteomalacia; however, secondary hyperparathyroidism often raises the serum calcium to low normal levels. The PTH-mediated increase in phosphate clearance often produces hypophosphatemia.
A 44-year-old man presents with worsening abdominal distension, edema, and jaundice. He has chronic viral hepatitis B and cirrhosis. Recently he has noticed decreased urine output despite adequate fluid intake. On examination he is icteric, the blood pressure is 110/70 mm Hg, pulse 74/min, JVP is 4 cm, heart sounds are normal, and there are tense ascites and pedal edema. Which of the following is an early manifestation of hepatorenal syndrome?
Hepatorenal syndrome frequently complicates hepatic failure. Although it can develop gradually, acute renal failure can also be precipitated by hemodynamic stresses (bleeding, diuresis). The earliest manifestations are intrarenal vasoconstriction and avid sodium retention.