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A 42-year-old woman has noticed dry skin, fatigue, and weight gain over the past 3 months. Her blood pressure is 110/70 mm Hg, pulse 60/min, and heart and lungs are normal. Her skin feels rough and dry, but the rest of the examination is normal. Her biochemistry is normal but the thyroid-stimulating hormone (TSH) is 39 mU/L (0.5–5 mU/L). Which of the following is the most likely cause for her elevated TSH?
Primary hypothyroidism is the most common cause of hypothyroidism in adults. Primary hypothyroidism is several times more common in women than in men and occurs most often between the ages of 40 and 60. Postablative hypothyroidism (radiation or surgery induced) is also very common.
A 53-year-old man has had gout for many years, and usually experiences 4–5 attacks a year. He is not on any medications for gout prophylaxis, and takes an over-the-counter nonsteroidal anti-inflammatory drug (NSAID) to treat his flares. On examination, there are no active joints presently, but he does have some tophaceous deposits on his left hand. As part of his complete evaluation, screening for renal complications is performed. Which of the following findings is most likely compatible with chronic gouty nephropathy?
Diminished concentrating ability and proteinuria occur even when the glomerular filtration rate is near normal. The severity of renal involvement correlates with the duration and magnitude of serum uric acid elevation. Uric acid and monosodium urate deposit in the renal parenchyma. These deposits can cause intrarenal obstruction and elicit an inflammatory response as well. Hypertension, nephrolithiasis, and pyelonephritis can also contribute to the nephropathy of gout.
Which of the following is the most common presentation of anterior pituitary hyposecretion in a 26-year-old woman?
With pituitary hypofunctioning, gonadotropin deficiency is the most common early manifestation in both men and women. Growth hormone secretion is also impaired early on, but is less clinically apparent
A 19-year-old woman presents with primary amenorrhea. Her physical examination is normal, and she has female sex characteristics and breast development. The only abnormality is the absence of body hair. Genetic testing reveals an XY chromosome pattern. Which of the following mechanisms is most likely to explain her phenotypic pattern and amenorrhea?
Disease states, due to abnormal intracellular receptors, include androgen insensitivity; cortisol resistance; vitamin D-dependent rickets, type II; thyroid hormone resistance; and pseudohypoaldosteronism. Androgen insensitivity syndrome is caused by a mutation in the androgen receptor, and it affects 1 in 100,000 chromosomal males. Because the androgen receptor is X-linked, it only affects males. The phenotypic presentation can vary from complete androgen insensitivity (female external features) to partial insensitivity causing ambiguous or normal male features and infertility. There are several different types of cell membrane receptors.
A 17-year-old woman has skin photosensitivity since childhood but has gotten worse recently. Her skin appears fine indoors, but within a short period of sun exposure, she develops burning, redness, and itching. A diagnosis of erythropoietic protoporphyria is made by a dermatologist. Which of the following treatments is most likely to be helpful?
Beta-carotene increases the patient’s tolerance for sunlight, apparently by quenching active intermediates. Beta-carotene is an effective scavenger of free radicals. Although many affected individuals can tolerate sun exposure while taking beta-carotene, it has no effect on the basic metabolic defect in porphyrin-heme synthesis.
A 23-year-old woman presents for evaluation of irregular periods and infertility. Her clinical examination is entirely normal. Biochemical tests show a reduced estradiol and folliclestimulating hormone (FSH) levels. She is diagnosed with central hypogonadism. Which of the following is the most important function of FSH?
FSH is said to encourage maturation of a follicle in the human menstrual cycle. The cardinal hormonal change in phase I is a rise in FSH caused by a decrease in the level of estrogens and a waning activity of the corpus luteum. In men, FSH stimulates Sertoli cells, which have an important role in spermatogenesis.
A healthy 42-year-old woman is found on routine blood testing to have a calcium level of 12 mg/dL. She feels well, and her physical examination is normal. Further investigations reveal a parathormone (PTH) level of 750 pg/mL (230–630 pg/mL). Which of the following findings is also associated with this disorder?
In hyperparathyroidism, bony lesions are lytic and can cause pain. The cortical surfaces are thinned and much of the bone is demineralized. The fibrotic bulging lesions within bone are termed brown tumors. Fluid-filled cysts can also occur (osteitis fibrosa cystica). Anemia is common, and the QT interval can be shortened if the calcium is high enough. Hypertension is common. Most patients with hyperparathyroidism have a simple adenoma that functions autonomously, so that hormone is secreted with high calcium. In about 10–15% of cases, hyperplasia of all the parathyroid glands (chief cell hyperplasia) is the cause. Differentiation from adenoma is important to determine the correct surgical approach but is, unfortunately, very difficult
A 32-year-old woman is feeling unwell because of muscle cramps and generalized fatigue. Her blood pressure is 120/70 mm Hg, pulse 100/min, and the heart and lungs are normal. Muscle strength and bulk are normal but the reflexes are increased symmetrically. She had a previous thyroidectomy for a goiter 3 years ago. Her serum calcium level is 7 mg/dL (8.4–10.2 mg/dL), TSH 3 mU/L (0.5–5 mU/L) and albumin 4 g/dL (3.5–5.5 g/dL). Which of the following is the most likely explanation for her low calcium?
Surgical removal is the most common cause of hypoparathyroidism. When the glands, or their blood vessels, have merely been damaged and not removed, tissue often regenerates. Hypoparathyroidism can frequently follow thyroid surgery. The incidence varies and depends on the extent of resection, the skill of the surgeon, and the degree of diligence in diagnosing hypocalcemia.
A 27-year-old woman presents with weight loss, fatigue, and weakness. She also experiences nausea and vomiting but no dysphagia. Her physical examination is normal except for increased generalized skin pigmentation. Her serum sodium is low and potassium is high. Which of the following features is also most likely to be present?
Water diuresis is impaired in adrenocortical insufficiency. Lack of aldosterone also favors the development of hyperkalemia and mild acidosis. The decreased circulating volume, secondary to aldosterone deficiency, is one of the factors resulting in elevated basal antidiuretic hormone (ADH) levels and thus hyponatremia.
A patient with polyuria and polydipsia is newly diagnosed with central diabetes insipidus (DI). Which of the following is the most likely finding on magnetic resonance imaging (MRI) of the brain?
Because DI is usually caused by destruction, or agenesis, of the posterior pituitary, its normal signaling is lost. Pituitary DI can also result from trauma, tumors (both primary and secondary), granulomas, infections, inflammatory diseases, chemical toxins, congenital malformations, and genetic disorders. Depending on the cause, the MRI may demonstrate other associated findings.
A 17-year-old man is 5’7” tall and weighs 370 lb. No medical cause for this “essential obesity” is found. Which of the following abnormalities can he also be expected to have?
Hypertriglyceridemia may result in part from hyperinsulinism, because insulin is one of the factors involved in lipoprotein secretion by the liver. With massive obesity, there is an increased prevalence of cardiovascular disease, hypertension, diabetes, pulmonary disorders, and gallstones. Young men with morbid obesity have a 12-fold higher mortality risk than the general population. Even in old age (65–74 years), the mortality is doubled in obese men. Cardiovascular disease is the most important factor.
A 56-year-old man presents with a change in skin color, fatigue, and abdominal pain. He has also noticed increased urine output and thirst. On examination, his skin appears bronze in color, his liver span is 16 cm, and there is loss of body hair, and testicular atrophy. His ferritin is 600 ng/mL (15–200 ng/mL), aspartate amino transferase (AST) 130 U/L (8–20 U/L), alanine amino transferase (ALT) 150 U/L (8–20 U/L), and total bilirubin 0.5mg/dL (0.1–1 mg/dL). Coagulation tests and albumin level are normal but the random glucose is elevated at 250 mg/dL. Which of the following is the most likely diagnosis?
High ferritin, hepatomegaly, skin changes, and diabetes suggest hemochromatosis. The arthritis is characterized by chondrocalcinosis, but, unlike idiopathic chondrocalcinosis, the hands are usually involved first. The arthropathy often progresses despite phlebotomy. Liver disease is usually the presenting feature. Skin pigmentation is predominantly by melanin. Heart failure is the most common cardiac problem. Addison’s does not involve the liver, and Wilson’s usually presents at an earlier age and does not cause diabetes. In amyloidosis, skin pigmentation is not a feature.
A 35-year-old man has had recurrent attacks of abdominal pain and proximal motor neuropathy since puberty. The episodes are precipitated by infections and certain medications. During one of the attacks, the plasma porphobilinogen levels were increased. Which of the following medications is not considered safe in patients with this condition?
In patients with acute intermittent porphyria, oral phenothiazines may be used for abdominal or muscle pains, and narcotics may also be used, but barbiturates should be avoided. Sulfonamides are unsafe, but penicillin and its derivatives are safe. Other unsafe medications include alcohol, carbamazepine, valproic acid, and synthetic estrogens and progestogens. Most heterozygotes remain asymptomatic unless a precipitating factor such as a drug or weight loss is present. Poorly localized abdominal pain is the most common symptom.
A 43-year-old man weighs 85 kg and is 1.8 m tall. His calculated body mass index (BMI) is 23 kg/m2. Which of the following conditions is he most likely at risk for?
One of the most efficient ways to define obesity is by BMI, which is calculated by weight/height2, calculated using kilograms for weight and meters for height. This man’s BMI is between 23 and 24 kg/m2 and confers no special risk. (The acceptable range is 20–25.)
A 47-year-old woman with bipolar disorder develops new symptoms of polyuria and polydipsia. She has been on lithium for a long time to control her illness. Which of the following is the most likely explanation for this complication of lithium treatment?
Nephrogenic diabetes insipidus is caused by a defect in the action of vasopressin on the renal tubules. This can be genetic, and variants include X-linked recessive, autosomal dominant, and autosomal recessive. Numerous drugs can cause the syndrome, as can many forms of renal disease. Hypercalcemia and hypokalemia can also cause the syndrome.
The 2-year-old daughter of a Jewish couple, whose parents emigrated from Russia, develops progressive loss of motor skills. There is macular pallor on ophthalmic examination, and she has a short stature, thin limbs, but full cheeks. She is also prone to developing hypoglycemia and lactic acidosis. Which of the following metabolic abnormalities is most likely associated with this disorder?
Glycogen storage is not characteristic of TaySachs disease. Ganglioside accumulation can now be diagnosed by decreased hexosaminidase in peripheral leukocytes. Tay-Sachs is characterized as a lysosomal storage disease. Mental retardation, seizures, blindness, and a retinal cherry red spot are characteristic. It is most common in Ashkenazi Jews and is inherited in an autosomal recessive manner
A 63-year-old man develops edema, and dyspnea on exertion. He has no prior cardiac or renal conditions, and his examination is significant for macroglossia, elevated jugular venous pressure (JVP), hepatomegaly, and 3+ pedal edema. His investigations reveal 3.5 g/d of protein in the urine, anemia, normal fasting glucose, and serum immunoelectrophoresis is positive for a monoclonal immunoglobulin. Which of the following is the most characteristic neurologic finding associated with this condition?
In addition to peripheral motor and sensory neuropathy, cardiac involvement, tongue enlargement, gastrointestinal (GI) manifestations, and carpal tunnel syndrome are also seen in amyloidosis. The specific diagnosis requires tissue biopsy with presence of amyloid with specific stains. In primary amyloidosis and myeloma, the amyloid protein is of the AL type. In reactive amyloidosis, the protein is of the amyloid A protein (AA) type.
A30-year-old man presents with recurrent flushing, diarrhea, and weight loss. His examination is normal. Lab investigations reveal an elevated urinary 5-hydroxyindoleacetic acid. Which of the following is the most likely diagnosis?
Carcinoid syndrome is characterized by increased levels of 5-hydroxyindolacetic acid. The syndrome occurs in relation to malignant tumors that have metastasized, usually with hepatic implants. Gastrointestinal carcinoids are most commonly found in the appendix. These are very slow growing, thus the 5-year survival rate is 99%. Many carcinoids are discovered as incidental findings on autopsy
A 25-year-old woman presents with symptoms of polyuria and polydipsia. So far investigations have ruled out psychogenic causes and diabetes. A fluid deprivation test is performed. At the end of the test, the urine osmolality is 240 mOsm/kg and the serum antidiuretic hormone (ADH) level is elevated. Which of the following is the most likely diagnosis?
Central diabetes insipidus is most commonly caused by a primary deficit in the secretion of vasopressin by the posterior pituitary. It is usually caused by agenesis or destruction of vasopressin-producing neurons by either a developmental, acquired, genetic, or idiopathic disorder. Nephrogenic diabetes insipidus is the failure of the kidney to respond to ADH. It can be acquired, genetic, or medication related
A 40-year-old man has lipid investigations suggesting familial hypercholesterolemia (increased cholesterol, increased low-density lipoprotein [LDL], and normal triglycerides). This condition is characterized by increased risk for premature atherosclerosis and by the occurrence of tuberous and tendon xanthomas. Before making the assumption of familial hypercholesterolemia, secondary causes need to be considered. Which of the following conditions is most likely to cause secondary hyperlipidemia?
In familial hypercholesterolemia, there is an increased incidence of CAD, and hypercholesterolemia occurs along with tuberous xanthomas, arcus senilis, and atheromas. Most affected individuals are heterozygous for the mutant gene. Important secondary causes include DM, obesity/dietary intake, hypothyroidism, renal disease (nephritic syndrome), and cholestatic liver disease. Alcohol usually improves lipid profiles in small amounts and in excess causes increases in triglycerides. Estrogen as well improves lipid profiles.