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Learn how to assess investigation results in patients by studying test forms, identifying abnormalities, listing differentials, and management plans based on the findings. Explore topics like anion gap, metabolic acidosis, glucose levels, and serum osmolality.
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NITMED TUTORIALS ASSESSING INVESTIGATION RESULTS
APPROACH -Pick up the test form and study it -Identify the patient details (name, age, ward and hospital number) -Describe what modality of investigation it is, and what date it was done. -Identify the abnormalities -List likely differentials -List possible management plan arising from the result.
Anion Gap AG = Na - (Cl + HCO3) The normal value for the serum anion gap is 8-16mEq/L. However, there are always unmeasurable anions, so an anion gap of less than 12 mEq/L is considered normal
Blood Glucose to convert to mmol/l, divide by 18. HYPOGLYCAEMIA Hypoglycemia is considered with blood glucose level of less than 70 mg/dL NORMAL RANGE : Fasting plasma glucose - 70-99 mg/dL Postprandial plasma glucose at 2 hours - Less than 140 mg/dL Random plasma glucose - Less than 140 mg/dL (Serum glucose values are 1.15% lower than plasma glucose values.) IMPAIRED GLUCOSE. Impaired fasting glucose - Fasting glucose of 100-125 mg/dL Impaired glucose tolerance testing - Postprandial glucose at 2 hours of 140-200 mg/dL DIABETES Fasting plasma glucose - Greater than 125 mg/dL Random plasma glucose - Greater than 200 mg/dL Postprandial glucose at 2 hours - Greater than 200 mg/dL
Serum Osmolality Calculated osmolarity = 2 Na + Glucose + Urea ( all in mmol/L). To calculate plasma osmolality use the following equation : = 2[Na+] + [Glucose]/18 + [ BUN ]/2.8[8] where [Glucose] and [BUN] are measured in mg/dL. Normal reference range of osmolality in plasma is about 275-295 milli-osmoles.
Conditions associated with increased serum osmolality include the following: Marked hyperglycemia, including diabetic ketoacidosis and nonketotic hyperosmolar hyperglycemic coma Diabetes insipidus (central and nephrogenic) Hypernatremia due to dehydration [1 Hypernatremia due to iatrogenic or accidental excessive sodium chloride (NaCl) or sodium bicarbonate (NaHCO3) intake Alcohol ingestion (eg, ethanol, methanol, ethylene glycol, polyethylene glycol) Conditions associated with decreased serum osmolality include the following: Hyponatremia with euvolemia (eg, psychogenic polydipsia, syndrome of inappropriate antidiuretic hormone (SIADH), hypothyroidism, adrenal insufficiency) Hyponatremia with hypervolemia (eg, cirrhosis, congestive heart failure, nephrotic syndrome)
Conditions associated with very high aspartate aminotransferase levels and ALT are as follows: Liver damage (acute viral hepatitis, toxins/drugs including acetaminophen overdose, acute fulminant hepatitis) Tumor necrosis GGT levels are increased in patients withliver diseases in general, including the following: [6] Hepatitis (acute and chronic) Cirrhosis Liver metastasis and carcinoma Cholestasis Alcoholic liver disease Primary biliary cirrhosis and sclerosing cholangitis
High alkaline phosphatase levels in the liver can indicate: Cirrhosis Hepatitis bile duct blockage Mononucleosis, Bone disorders,such as Paget's Disease of Bone, Rickets, bone malignancies. Moderately high levels of alkaline phosphatase may indicate conditions such as Hodgkin lymphoma, heart failure, or severe bacterial infection.
Clinical Implications: Cardiovascular disease is the No. 1 cause of death in the United States, with an estimated 1.5 million heart attacks and 5 million strokes occurring annually – many in individuals who have no prior symptoms. Prevention of ischemic cardiovascular events is of fundamental importance. Risk factors – including age, smoking status, hypertension, diabetes, cholesterol, and HDL cholesterol – are used to identify individuals likely to have an ischemicevent.37
Due to the D-dimer test’s high sensitivity and poor specificity, a positive test (>400-500 ng/mL) does not indicate a VTE. If a patient has a high pretest probability (Well’s Clinical Prediction Rules) of developing a VTE, anticoagulant therapy is initiated, regardless of D-dimer test results. Older age, infections, burns, and heart failure can result in an elevated D-dimer test. If a patient has low pretest probability and has a high D-dimer, further testing (duplex ultrasound) iswarranted.42
Urinalysis Colour Quantity Turbidity Smell The Cockcroft and Gault formula (1973) CCr={((140–age) x weight)/(72xSCr)}x 0.85 (if female) Abbreviations/ Units CCr (creatinine clearance) = mL/minute Age = years Weight = kg SCr (serum creatinine) = mg/dL