Glucagon is made by the -cells in the pancreas and when released causes elevated blood glucose. By what mechanism does glucagon promote hyperglycemia?
Glucagon stimulates glycogenolysis and gluconeogenesis.
What is characteristic of type 1A diabetes mellitus?
Circulating autoantibodies formed against pancreatic insulin-secreting cells.
Glycated hemoglobins are formed by the addition of glucose to the ___-terminal _____ residue.
Determining urinary albumin excretion (UAE) is critical in type 1 and type 2 diabetics because:
increased UAE is highly predictive of and is thought to precede diabetic nephropathy and end-stage renal disease.
The role of the clinical laboratory in diagnosis of diabetes mellitus involves initial diagnostic criteria. For many years, the only diagnostic criterion required was demonstration of hyperglycemia in two or more fasting plasma glucose tests. What other laboratory analysis is now considered to be useful as a diagnostic criterion?
Demonstration of elevated hemoglobin A1c
The syndrome that is considered a collection of associated clinical and laboratory findings that include insulin resistance, hyperinsulinemia, obesity, high triglyceride and low high-density lipoprotein (HDL) cholesterol, and hypertension is the:
insulin resistance syndrome.
Type 2 diabetes mellitus:
is associated with resistance to the action of insulin.
A pregnant woman at 27 weeks gestation is screened for gestational diabetes mellitus. Plasma venous glucose was measured at 1 hour following a 50 g oral glucose load. What value must this glucose be above or equal to for a glucose tolerance test to be performed?
The value must be 140 mg/dL glucose.
Insulin regulates blood glucose levels by:
stimulating the translocation of a glucose transporter and promoting glucose uptake into skeletal muscle and fat.
Factors identified as associated with (and possibly causing) type 1 diabetes mellitus include all of the following except:
A woman visits her physician with a complaint of polyuria and polydipsia. She has a family history of type 2 diabetes mellitus and is concerned that she is developing the disease. The physician notes that her previous hemoglobin A1c (Hb A1c) value was 6% (considered within healthy reference interval in the physician’s practice) with a fasting plasma glucose of 95 mg/dL. At this visit, her Hb A1c value is 8.5%. Why would the physician be correct to order an oral glucose tolerance test (OGTT) for this individual?
The Hb A1c result indicates an increase in average blood glucose and possible
onset of type 2 diabetes. An OGTT would help to confirm this.
Hb A1c makes up approximately what percentage of total Hb A1?
Retinopathy, neuropathy, microvascular, and macrovascular changes are all chronic complications of both type 1 and type 2 diabetes mellitus. One theory as to the cause of these chronic problems is the elevation of advance glycation end (AGE) products. These AGE products consist of:
proteins that have been irreversibly modified by nonenzymatic attachment of glucose.
Insulin deficiency in diabetes mellitus will cause:
increased glucagon concentration, which contributes to hyperglycemia and ketosis.
What 2-hour plasma glucose oral glucose tolerance test (OGTT) results would be classified as diagnostic for impaired glucose tolerance if an individual’s fasting blood glucose value is 120 mg/dL (healthy glucose reference interval is 74 to 99 mg/dL)?
A fingerstick glucose value was 120 mg/dL. If unhemolyzed serum or plasma were tested from the same individual at the same time, what might the glucose value be?
Approximately 132 mg/dL
The development of ketoacidosis in an uncontrolled diabetic is caused by the:
increased formation of -hydroxybutyric acid.
An individual with a severe, uncontrolled case of type 1 diabetes mellitus will exhibit all of the following laboratory results except:
As a counter-regulator of glucose metabolism in a healthy individual, epinephrine has the effect of _____ blood glucose.
stimulating glycogenolysis to increase
High albuminuria is defined as:
increased urinary albumin excretion between the range of 20 to 200 µg/min that is measured by the laboratory in the chronic management of diabetes mellitus.
Although not a routine clinical laboratory screening test, measurement of insulin secretion in a potential diabetic is important because:
a decrease in glucose-stimulated insulin secretion is the first functional abnormality in both types of diabetes.
The hyperglycemia observed in a diabetic causes many toxic effects such as retinopathy and nephropathy. Although it is unclear how these outcomes are caused by elevated blood sugar, it is thought that hyperglycemia:
causes increased production of advanced glycation end products, which might contribute to microvascular complications.
What antibodies is found most commonly in over 90% of children who develop type 1 diabetes before 5 years old?
What cardiac biomarkers is elevated about 50 times the upper limit of normal at 24 hours after onset of an acute myocardial infarction?
Why would high-sensitivity C-reactive protein (CRP) be an indicator of a potential myocardial infarction?
It is an acute phase reactant plasma protein that rises in response to inflammation and the atherosclerotic process.
An ideal cardiac marker should be elevated in the circulation for how long following a cardiac event?
At least several days
A 55-year-old man is taken to a hospital emergency department by helicopter following a rural automobile accident that occurred approximately 3 hours ago. The man, who is having difficulty speaking to the EMTs, is clutching his chest. Upon the man’s arrival, the emergency room physician orders a cardiac marker panel that includes serum CK, CK-2 (CK-MB), troponin, and myoglobin. The CK-2 value was less than 2% of total CK, which was slightly increased; troponin was normal; and the myoglobin was increased 3 times the upper limit of normal. The physician has asked the laboratory to explain the findings. What represents the lab’s explanation?
Trauma caused by the accident with possible crush injury to the chest caused elevated myoglobin with normal troponin and CK-MB.
What cardiac markers is elevated for the longest period of time after a myocardial infarction?
What is considered to be the most specific marker for adverse ventricular remodeling following an acute myocardial infarction?
Brain natriuretic peptide (BNP)
In regard to cardiac anatomy, the myocardium:
contains bundles of striated muscle fibers.
What specimen types and collection methods is best for laboratory assessment of brain natriuretic peptide (BNP) in the evaluation of congestive heart failure?
EDTA-anticoagulated whole blood or plasma in plastic blood collection tubes only
Laboratory measurements for brain natriuretic peptide (BNP) be reported in:
A cardiac marker that increases progressively with increasing severity of disease and is not increased (or decreased) in conditions that mimic congestive heart failure is:
B-type natriuretic peptide.
The most common laboratory method used to assess brain natriuretic peptides is:
What troponins appears as uncomplexed or free following myocardial injury?
In a point-of-care (POC) test for a cardiac biomarker used in the evaluation of an individual with possible acute coronary syndrome, what is a Laboratory Medicine Practice guideline of the National Academy of Clinical Biochemistry (NACB)?
POC assays should provide quantitative results.
Chest pain that is associated with a decrease in oxygen supply to the heart muscle but that exhibits no cellular necrosis based on cardiac troponin value and is considered a less severe event is referred to as:
In the process of atherosclerotic plaque formation, what is the typical precipitating event?
Damage to the endothelium of cardiac blood vessels
The protein in cardiac muscle fibers that regulates contraction is:
Regarding assessment of congestive heart failure, NT-proBNP can be measured. This protein is:
the N-terminal fragment of pro-BNP.
In your clinical chemistry laboratory, you use an immunoassay to detect blood levels of NT-proBNP. You receive a filled green-top anticoagulant-containing plastic blood collection tube with a request for NT-proBNP. What is your next step?
Proceed, because this tube contains heparin and provides plasma after centrifugation, which is acceptable for the NT-proBNP assay.
What are the laboratory results for CK-MB and cardiac troponin in the following conditions: muscular dystrophy, polymyositis, and extreme physical activity?
CK-MB elevated, troponin normal
A 36-year-old individual visits her physician with a complaint of nausea, loss of appetite, weakness, and an inability to concentrate. Laboratory results indicate increased serum urea and creatinine, increased potassium, reduced glomerular filtration rate (GFR), low blood pH, anemia (low red blood cell count), and hypocalcemia. What is the likely diagnosis?
The portion of a nephron considered the most metabolically active and that is involved in the reabsorption of 60% to 80% of the glomerular filtrate and that secretes 90% of hydrogen ion excreted by the kidney is the:
A patient with elevated serum nitrogen compounds, markedly reduced GFR, increased serum sodium and potassium, and metabolic acidosis is diagnosed with acute kidney injury (AKI). What is a likely cause?
Decreased cardiac output
What laboratory results would point to a diagnosis of acute nephritic syndrome in an individual who exhibits hypertension and edema?
If a physician requests a creatinine clearance on an individual, what is the physician attempting to determine?
Glomerular filtration rate (GFR)
What components of the renal system is most important for regulation of plasma electrolytes and acid-base balance?
Distal convoluted tubule
In homeostatic regulation of plasma acid-base concentrations, sodium is both actively and passively exchanged in the tubules for what ions?
What statements regarding creatinine is correct?
Normal plasma creatinine does not always indicate normal kidney function.
Secretion of renin and aldosterone is induced by low blood pressure and volume. Renin is synthesized in the _____ and aldosterone is made in the _____.
kidney; adrenal gland
Secretion of renin and aldosterone is induced by low blood pressure and volume. What other hormone would be released in the event of low blood pressure and volume?
A 45-year-old man visits his physician with complaints of insatiable thirst, sudden onset of fatigue, polydipsia, and polyuria. Laboratory results indicate a normal fasting blood sugar. Serum sodium was slightly elevated. Urine was clear and had low specific gravity (hypotonic). The most likely cause of these symptoms and laboratory results would be:
Upon microscopic examination, an individual’s urine shows many bacteria, white blood cells, and cellular casts composed of polymorphonuclear leukocytes. It is likely that this individual has:
If an individual has a normal GFR and a hyperchloremic normal anion gap metabolic acidosis with a freshly voided early morning urine specimen which has a pH of 6.5, what is the likely diagnosis?
There is likely the onset of distal renal tubular acidosis (RTA).
Damage to the glomerulus would be suspected when the urine sediment contains:
red blood cell casts.
Why is bone disease a consequence of chronic kidney disease (CKD)?
When glomerular filtration declines, vitamin D activation decreases resulting in reduced calcium, which further leads to resorption of calcium from bone.
You have been asked what laboratory tests should be requested to assess the electrolyte balance regulatory function of an individual’s kidneys. What is your reply?
Serum sodium and potassium, and arterial blood pH
The major artery that expands into the capillary bed that forms the glomerulus is the:
The most common glomerular disease worldwide is:
A 46-year-old patient visits her physician with a complaint of chest pain, blood in her urine, and oliguria. She states that these symptoms have gotten worse over the past 2 to 3 months. Urine and blood samples are collected. Urine GFR is calculated to be 40 mL/min/1.73 m2 and hemoglobin is 8 g/dL. Urine protein was elevated, with the presence of red blood cell casts. Upon review of her health history, it was noted that she was a cigarette smoker with hypertension. The most likely diagnosis in this case would be:
chronic kidney disease (CKD).
In an individual with chronic kidney disease, what might be the predominant cause of the low hemoglobin value and anemia?
Decreased erythropoietin synthesis
An individual presents to his physician with generalized weakness and fatigue. Blood is collected and an elevated WBC count with lymphocytosis is noted. Serum protein is moderately decreased, but the urine reagent dipstick does not indicate proteinuria. Upon confirmatory testing with a precipitation test, the urine protein is 4+. Based on other symptoms, the physician suspects multiple myeloma. What might be the cause of the discrepancy in urine protein values?
Reagent dipsticks respond mostly to urine albumin and not to other proteins.
In multiple myeloma, what protein is likely causing an elevated value in the urine protein confirmatory test?
Bence Jones protein
The volume of plasma from which a substance is completely removed by the kidneys per unit of time is the definition of:
What is the correct formula for determining glomerular filtration rate?
GFR = ([urine concentration of the substance] volume)/[plasma concentration of the substance]
An individual is brought to the emergency department of a local hospital with signs of narcotic overdose and respiratory depression. What acid-base status would this individual have?
A person suspected of having chloride responsive metabolic alkalosis caused by prolonged vomiting would exhibit what?
Primary bicarbonate excess
In regard to respiration, peripheral chemoreceptors located in the carotid arteries and aorta are stimulated by:
pH and PO2 content of blood.
An overweight 55-year-old single woman from a rural farming area was brought to the emergency department by her neighbor. The woman had a large abscess on the bottom of her foot; she was irritable and complained of blurred vision and of being thirsty. Her breathing was rapid. The neighbor said that the only medication the woman was using was for blood pressure and sometimes an aspirin. Blood and urine samples were collected. Arterial blood gas results were: pH 7.2; PCO2 47 mm Hg; HCO3 8 mmol/L. Blood glucose was 340 mg/dL and a high anion gap was calculated. Urine glucose and ketones were markedly increased. Based on the laboratory values, what state of acid-base balance is this patient in?
An overweight 55-year-old single woman from a rural farming area was brought to the emergency department by her neighbor. The woman had a large abscess on the bottom of her foot; she was irritable and complained of blurred vision and of being thirsty. Her breathing was rapid. The neighbor said that the only medication the woman was using was for blood pressure and sometimes an aspirin. Blood and urine samples were collected. Arterial blood gas results were: pH 7.2; PCO2 47 mm Hg; HCO3 8 mmol/L. Blood glucose was 340 mg/dL and a high anion gap was calculated. Urine glucose and ketones were markedly increased. Based on the laboratory values and symptoms of the woman, what is the most likely cause of her acid-base disorder?
Hypernatremia commonly occurs with:
decreased synthesis of antidiuretic hormone (ADH).
Hypokalemia may be seen in all of the following except:
decreased glucocorticoid concentration in blood.
What is the anion gap given the following serum electrolyte data: Na = 132 mmol/L, Cl– = 90 mmol/L, HCO3– = 22 mmol/L, K = 4 mmol/L?
Determine the anion gap given the following serum electrolyte data: Na = 132 mmol/L, Cl = 90 mmol/L, HCO3– = 22 mmol/L, K = 4 mmol/L. Is the anion gap you calculated within the healthy reference interval?
What conditions will cause an increased anion gap?
All of the following are causes of hyponatremia with concomitant decreased plasma osmolality and normal volume status except:
Metabolic organic acidoses typically present with an increased anion gap. In contrast to these, inorganic acidosis with a normal anion gap is typically caused by:
loss of bicarbonate-rich fluid via the kidneys or gastrointestinal tract.
An individual visits a physician with the complaint of nausea, mental confusion, and needing an excessive amount of salt all the time. Laboratory results indicate decreased serum sodium and low serum osmolality. Physical examination reveals hypovolemia with low orthostatic blood pressure and tachycardia. A urine sodium analysis was suggested by a laboratorian and urine sodium was found to be increased; the physician diagnoses a salt-losing nephropathy (a renal tubule disease). What type of electrolyte disorder is this?
A hospitalized patient in the ICU has cirrhosis. After a period of time, the heart and kidneys begin to fail and the patient develops edema. What type of electrolyte disorder would develop from this situation?
How do healthy kidneys compensate for the excess hydrogen ions and concurrent low pH observed in metabolic acidosis?
Increasing excretion of acid
How do healthy lungs compensate for the decrease in pH in a state of metabolic acidosis?
Physiologically important buffers maintaining body pH include all of the following except:
At physiological pH of 7.4, what contributes most to the total serum CO2 (think about the equilibrium of the reaction in the formula)?
Hypokalemia (<3.0 mmol/L) is considered a serious health threat because
the heart rate increases, leading to weakness, difficulty in breathing, and eventual cardiac arrest.
The most important buffer of plasma is the _____ system.
The metabolic component of acid-base regulation is the renal system. What statements concerning this component is incorrect?
In the metabolic component, the renal system responds immediately to a change in acid-base status.
What hormones is an active regulator of water retention/reabsorption in the kidney?
What hormones is an active regulator of sodium (and passive controller of water) in the kidney?
A 17-year-old woman was brought by her friends to the emergency room in an agitated state. She stated that she had broken up with her boyfriend and he had threatened her. Her temperature was 101° F, and she was breathing rapidly. She claimed that she could not slow her breathing down despite attempts to have her breathe deeply. An arterial blood gas revealed a pH of 7.54, HCO3 of 18 mmol/L, and PCO2 of 28 mm Hg. What is occurring in this patient?
Excess elimination of acid via the respiratory route
The major risk factor for development of hepatocellular carcinoma is:
infection with hepatitis B or C viruses.
__ In chronic liver failure, such as cirrhosis, there is a significant impairment of normal ammonia metabolism and eventual hyperammonemia. Elevated ammonia can lead to:
_ The functional unit of the liver is the:
_ You operate a laboratory that receives many serum specimens from the Billy Rubin Memorial Liver Clinic next door. The patients who go to this clinic have serious acute and chronic liver diseases. Would you expect to see increased or decreased plasma albumin from the liver patients who go to this clinic?
_ Bilirubin that is attached to albumin before it is transported across the hepatocyte membrane is called:
The type of RNA virus that is considered to be the cause of the most common type of acute hepatitis that does not lead to chronic hepatitis is:
hepatitis A virus.
_ A 53-year-old man notices the whites of his eyes seem a bit yellow, there is swelling in his abdomen, and he is often fatigued. He tells his physician that he enjoys “a few” martinis every night. Upon physical examination, the physician notes decreased weight, elevated blood pressure, jaundice, and ascites, and laboratory results indicate decreased albumin, low platelet count, increased prothrombin time, and increased serum liver enzymes with AST activity higher than ALT. All viral hepatitis and cholestasis testing is negative. What is the likely diagnosis?
Chronic alcoholic hepatitis transitioning to cirrhosis
In the liver, ammonia is metabolized to form:
An autoimmune disease caused by an antibody directed toward the mitochondria of biliary epithelial cells that results in hepatic inflammation and portal hypertension is:
primary biliary cirrhosis.
The first protein marker to appear approximately 1 to 2 months after infection with the hepatitis B virus and also the last marker to disappear is the:
hepatitis B surface antigen.
What is not a consequence of portal hypertension in an individual?
A new intern calls the laboratory to ask which liver enzymes would be best to assess to differentiate between hepatocellular and cholestatic disease. You respond:
AST, ALT, and ALP.
Which type of hepatitis is a leading cause of chronic hepatitis and is caused by a mutating RNA virus?
What is considered a mechanism by which a membrane-bound enzyme, such as alkaline phosphatase, is released from a hepatocyte into blood?
Bile acids solubilize membrane-bound enzymes.
A 30-year-old man sees his physician with complaints of pruritus, fever, and pain around his abdomen and right side that he says “have been there a while but suddenly got really bad.” Laboratory results on his blood sample indicate elevated conjugated and unconjugated bilirubin and elevated alkaline phosphatase activity. There are no signs of chronic hepatitis or ascites. Gallstones are ruled out, and the physician notes that a previous diagnosis of ulcerative colitis had been made. What is the likely current diagnosis?
Primary sclerosing cholangitis
Prognosis in cirrhosis is based on a MELD score, which is also used to prioritize cases for liver transplantation. What laboratory values are used to calculate the MELD score of an individual?
Bilirubin, creatinine, and INR
Liver disease is classified as either acute or chronic. Acute liver disease takes the general form of either acute hepatitis or:
Regarding the gastrointestinal (GI) tract, the function of gastrin is to:
stimulate release of GI hormones, such as secretin and insulin.
What peptide hormones acts to increase intestinal motility and stimulate gallbladder contractions?
What substances is not synthesized by the pancreas?
Vasoactive intestinal polypeptide (VIP)
Extremely elevated serum levels of gastrin are typically indicative of:
What special specimen requirements must be met when collecting and preparing a sample for gastrin analysis?
Blood must be collected into a heparin-containing tube, separated in a refrigerated centrifuge, and frozen within 15 minutes of collection.
What statements concerning secretin is correct?
Secretin stimulates release of pancreatic hormones.
A problem with the use of noninvasive testing for assessing pancreatic exocrine function is that this type of testing:
lacks the clinical sensitivity and specificity for early disease detection.
An autoimmune disorder produced by ingestion of gluten and characterized by inflammatory damage to intestinal lining cells and malabsorption is:
The use of the urea breath test for detection of H. pylori involves:
bacterial hydrolysis of ingested labeled urea producing labeled bicarbonate, which is absorbed into the blood and exhaled as 14CO2 or 13CO2.
A consequence of Crohn disease is bacterial overgrowth of the small bowel that normally contains few bacteria. Bacterial overgrowth further leads to:
bile salt deficiency and fat malabsorption.
Secondary acquired lactose intolerance can occur from reduced lactase activity following diffuse intestinal damage caused by, for example, inflammatory bowel disease (IBD). What IBDs affects the large bowel in particular?
During the gastric phase of the digestive process, HCl will be released from parietal cells following the _____ of gastrin from the mucosal endocrine cells in the stomach.
Chronic pancreatic damage leads to pancreatic insufficiency. In children, this is most commonly associated with:
A peptide secreted by the upper intestinal mucosa that causes gallbladder contraction and release of digestive enzymes from the pancreas, and is also localized in the nervous system, is:
Mucosal inflammation of the stomach that is associated with peptic ulcer disease or gastric carcinoma is referred to as:
Fecal osmot Fecal osmotic gap measurements are done to:
distinguish between osmotic and secretory diarrhea.
Gastrointestinal neuroendocrine tumors are either carcinoid tumors of enterochromaffin cells or, as in the case of somatostatinoma, tumors of the:
pancreatic endocrine cells.
A 23-year-old man visits his physician with symptoms of abdominal discomfort and diarrhea. The man states that the diarrhea has been present off and on for approximately 6 weeks. He especially notes symptoms after a breakfast of wheat cereal and milk. His physician considers the possibility of two disorders, celiac disease and lactose intolerance. What pairs of laboratory tests would provide a definitive answer?
Analysis of tissue transglutaminase IgA antibodies and breath hydrogen testing
A test that is considered diagnostic for cystic fibrosis in infants over the age of 2 weeks and for other assessment of pancreatic insufficiency is:
The primary physiological regulator of parathyroid hormone (PTH) synthesis and secretion is:
the concentration of free calcium in blood or extracellular fluid.
Rickets is sometimes associated with deficiency of what vitamins?
Hypoparathyroidism is most commonly caused by:
parathyroid gland destruction.
What makes up the organic matrix component of bone?
Calcium, protein, and collagen
osteoblasts are the bone-forming cells.
The major cause of the decrease in total bone mass in an aging osteoporotic woman is:
being postmenopausal and estrogen deficient.
An individual’s serum phosphate level is decreased but his physician cannot determine a physiological basis for this abnormal result. What could possibly have caused this result?
Use of IV carbohydrate therapy to stimulate insulin secretion
are proteins found in bone whose serum level can reflect bone formation.
An individual has the following laboratory test results: increased serum calcium, decreased serum phosphorus, increased parathyroid hormone. This individual most likely has:
Total serum calcium:
In a case of severe osteomalacia, would bone-specific alkaline phosphatase be increased, decreased, or remain unchanged?
A noncollagenous protein marker of bone formation that is released from bone during bone resorption, regulated by 1,25-dihydroxyvitamin D, and synthesized by osteoblasts and that regulates insulin secretion and sensitivity is:
Hypercalcemia occurs in humoral hypercalcemia of malignancy (HHM) because:
PTH-related protein (PTHrP) is synthesized by tumors and stimulates bone resorption.
The clinical usefulness of calcitonin measurement is:
as a tumor marker for medullary thyroid carcinoma.
What diseases is characterized by a loss in bone mass?
What analytes is most useful in distinguishing primary from secondary hyperparathyroidism?
In a case of osteomalacia related to vitamin D deficiency, would serum calcium be increased, decreased, or remain unchanged?
A blood specimen is collected in a heparin-containing tube for calcium and magnesium determination. Upon centrifugation, the plasma appeared hemolyzed. How would this affect the magnesium value?
Because erythrocytes contain magnesium, hemolysis would increase its apparent value.
Hypophosphatemia is seen in all of the following except:
decrease produces neuromuscular excitability.
Hypermagnesia may be observed in all of the following except:
A factor that would alter protein binding of calcium and its redistribution among the three plasma pools would be:
What is a recognized clinical feature of hypercalcemia?
Specimen requirements for assessing free calcium using ion-selective electrode methodology include: