Advanced CSMLS Chemistry Quiz: Blood Gas Analysis and Buffer Systems

The correct clinical reasons for an abnormal blood gas result are related to oxygen saturation, carbon dioxide retention, and renal function. Conditions like airway blockage, COPD, and renal problems can lead to abnormalities in blood gas results, while unrelated issues like headaches, broken arms, or colds would not directly impact blood gas levels.

When there is a delay in sample processing, cellular respiration continues leading to changes in blood gas results. The correct answer outlines the specific changes seen in pCO2, pO2, pH, potassium, and glucose levels.

Arterial blood gas tests are commonly used to assess a patient's oxygen and carbon dioxide levels as well as the acidity (pH) of the blood. The normal reference ranges for arterial pH, pO2, and pCO2 are pH 7.35 - 7.45, pO2 80 - 100 mmHg, and pCO2 35 - 45 mmHg respectively. Any values outside of these ranges may indicate underlying health issues.

During acidosis, the respiratory system compensates by increasing ventilation (hyperventilation) to blow off carbon dioxide (decreased pCO2), which helps shift the body's pH back towards normal.

Deoxyhemoglobin refers to hemoglobin that is not bound to oxygen. Hemoglobin has the capacity to carry up to 4 molecules of oxygen, facilitating the transport of oxygen in the blood stream.

Sulfhemoglobin is a compound in which hemoglobin is bound to sulfur, and this bond is irreversible. It cannot be reversed by medication, dietary changes, or blood transfusions. It remains in the bloodstream until the red blood cell completes its life cycle.

In cases where there's a delay in centrifugation after collection, certain chemistry analytes continue to leak out of red blood cells, causing an increase in their levels. Options 1 and 3 include analytes that are generally not impacted by delayed centrifugation, while option 2 presents a mix of analytes that are unrelated to the given scenario.

RCF stands for Relative Centrifuge Force, and it is calculated using specific formulas that involve the radius of the rotation (r), RPM, and constants. The correct formulas provided in the answer give the accurate method to calculate RCF in different units.

Hemolysis can lead to release of intracellular components from red blood cells, causing an increase in various analytes such as Potassium, LD, AST, ALT, IRON, AMMONIA, Mg, Phosphorus, and Protein.

Smoking before collection can result in a falsely elevated ammonia level due to the breakdown of urea in the saliva, leading to an increase in ammonia production.

Conditions such as dehydration, multiple myeloma, amyloidosis, and chronic infections can lead to an increase in total protein levels due to various underlying mechanisms. The incorrect answer choices have different underlying pathophysiologies that are not typically associated with elevated total protein levels.

The correct answer includes conditions that lead to decreased total protein levels through various mechanisms, such as loss of protein in urine, impairment in protein production, increased demand during pregnancy, and protein depletion due to burns. Dehydration, Cushing's syndrome, and hyperthyroidism do not directly result in decreased total protein levels as mentioned in the correct answer.

AST (Aspartate Aminotransferase) is an enzyme found in various tissues of the body, but particularly in the liver, heart, and skeletal muscles. Increased levels of AST in the blood are often associated with liver diseases/hepatocellular damage, heart conditions, and skeletal muscle disorders. Kidney diseases, lung infections, and neurological disorders are not typically linked to elevated AST levels.

The correct answer includes conditions such as biliary disorders, bone disease, parathyroid disorders, and intestinal disorders, all of which are known to cause increased ALK-Phos levels. Hypothyroidism, lung cancer, and diabetes are not typically associated with elevated ALP levels.

Calcium plays a crucial role in various physiological functions such as cardiac output, coagulation, and neuro-muscular transmission. It is not directly involved in aiding digestion, regulating body temperature, or stimulating hair growth.

Hypocalcemia can be caused by a variety of factors including renal failure where the kidneys are unable to retain calcium, leading to low levels in the blood. Alkalosis, a condition where the body's pH is elevated, can also contribute to hypocalcemia. However, hypervitaminosis D, hyperparathyroidism, and acromegaly are not typically associated with causing hypocalcemia.

Potassium is an essential mineral that plays a crucial role in maintaining proper cardiac function and also regulates skeletal muscle contractions. The incorrect answers do not accurately reflect the primary functions of potassium in the body.

Hyperkalemia is primarily associated with renal failure and acidosis due to impaired kidney function leading to difficulty in eliminating potassium from the body, or shifts in potassium from the cells to the bloodstream. Hypokalemia, hypertension, and hypernatremia are conditions with opposite electrolyte imbalances.

Hyponatremia is a condition where there is a low level of sodium in the blood. Some common causes include excessive water intake (water intoxication), renal failure affecting the kidney's ability to regulate sodium levels, and taking diuretics which can lead to increased sodium loss. Dehydration, hypernatremia (high sodium levels), and hypokalemia (low potassium levels) are not direct causes of hyponatremia.

The correct levels of pO2 and pCO2 in atmospheric air are around 150 mmHg and 1 mmHg respectively. These values are crucial for maintaining normal gas exchange in the lungs and tissues.

The pKa of the bicarbonate buffer system is 6.1, which determines the equilibrium between bicarbonate (HCO3-) and carbonic acid (H2CO3). The approximate pH when there is a 20:1 ratio of bicarb to carbonic acid is 7.4, representing a slightly alkaline solution.

Carboxyhemoglobin is a complex of hemoglobin and carbon monoxide (CO). Although the bond between hemoglobin and CO is reversible, hemoglobin has a 200 times greater affinity for CO than for oxygen, making it difficult to reverse the bond.

Methemoglobin is hemoglobin with oxidized iron Fe3+ (ferric) which cannot carry oxygen. However, it can be reversed by forcing the reduction of Fe3+ iron into Fe2+ ferrous iron with the help of methemoglobin reductase enzyme found in red blood cells.

When handling an ammonia specimen with the chemistry analyzer down, it is important to follow specific handling procedures to ensure accurate results when the equipment is operational again. Cold spinning and refrigerating the specimen or freezing it for longer down times helps preserve the integrity of the sample for analysis.

Hypokalemia is a condition characterized by low levels of potassium in the blood, commonly associated with alkalosis, insulin overdose, vomiting/diarrhea, nephritis, and diuretic use. Hyperkalemia is the opposite, with high levels of potassium. Hypomagnesemia is low magnesium levels, not potassium. Cushing's syndrome is not directly associated with hypokalemia.

Hypernatremia is a condition characterized by high levels of sodium in the blood. It is caused by a lack of water intake relative to the amount of sodium in the body. The incorrect answers provided do not align with the causes of hypernatremia.

In drug screening tests, a result that matches or exceeds the cut-off value is considered positive, indicating the presence of the substance being tested. Options stating inconclusive or higher/lower than cut-off are not accurate in this context.

Urine drug screens can be done on refrigerated samples up to 48 hours old, making the correct answer 'Yes'. It is important to follow proper storage guidelines to ensure accurate results.

Chemistry analytes like glucose, ionized calcium, and bicarbonate can be altered if there is a delay in centrifugation due to possible metabolic changes or interaction with blood components. The incorrect answers were chosen to provide a distractor pattern that includes other common chemistry analytes that are not typically affected by delayed centrifugation.