Blood Work Interpretation, Nashville Veterinary Specialists, Kelly Wang, DVM, MS, DACVIM

The speaker emphasizes the importance of understanding blood work beyond just recognizing what's 'normal' or 'abnormal'. They discuss the need to know the origins and meanings of various tests to better remember disease processes and consider why treatments work or don't. The talk aims to provide a comprehensive review, hoping to offer valuable insights even to those already familiar with blood work. The speaker also touches on the complexity of interpreting sodium levels and the challenges it presents, deciding to exclude it from the presentation to avoid confusion.

This paragraph delves into the intricacies of reference intervals in blood work, highlighting their dependence on the instrument and the fact that they represent a skewed population distribution. It's noted that normal ranges can vary, with 5% of normal animals potentially having values outside the typical 90% interval. The discussion also includes the impact of age, with adult reference ranges not always applicable to young animals, and the importance of considering the source of lab results due to variability among different labs.

The speaker discusses the importance of not solely focusing on whether blood work values are within the normal range, as animals can be dehydrated and still show normal albumin levels. The potential for misinterpretation is highlighted, especially in cases where dehydration is corrected and albumin levels drop. The paragraph also touches on the complexity of interpreting individual tests and the value of considering them in groups related to specific organ systems.

This section critiques the use of amylase and lipase tests for diagnosing pancreatitis, noting their lack of specificity due to their presence in various tissues and their clearance primarily through the kidneys. The discussion includes the impact of steroids on lipase levels and the challenges this poses for accurate diagnosis. The introduction of the Spec cPL test as a more reliable indicator of pancreatitis is mentioned, along with its limitations and the importance of considering the whole clinical picture.

The speaker explores the relationship between cholesterol levels and endocrine disorders such as hypothyroidism, diabetes, and Cushing's disease. They discuss the mechanisms by which these conditions can lead to increased cholesterol levels, including issues with lipoprotein metabolism and the impact of insulin resistance. The paragraph also touches on the significance of cholesterol in the context of pancreatitis and the potential for it to be elevated in certain breeds predisposed to hyperlipidemia.

This paragraph focuses on liver enzymes, particularly ALP and GGT, and their role as markers for liver disease. The discussion differentiates between isoenzymes and isoforms, and the impact of steroids on ALP levels. The speaker notes the importance of considering the half-life of these enzymes and the potential for drug-induced increases. The paragraph also addresses the use of GGT as a marker for biliary tract disease and its utility in differentiating between primary liver disease and secondary liver changes due to other conditions.

The speaker discusses bilirubin as a liver function test, explaining the process of its production from the breakdown of red blood cells and its conjugation in the liver. The paragraph differentiates between pre-hepatic, hepatic, and post-hepatic hyperbilirubinemia, and the associated conditions for each type. The importance of considering the speed of bilirubin increase and its impact on clinical signs is highlighted, along with the potential for functional cholestasis without physical obstruction.

This section examines the significance of plasma proteins, including albumin, fibrinogen, and globulin, in maintaining oncotic pressure. The discussion covers the impact of low albumin levels on plasma protein levels and the potential causes of low albumin, such as liver insufficiency, increased acute phase proteins, and intestinal loss. The paragraph also touches on the use of colloid fluid support in cases of low total plasma proteins and the importance of checking blood pressure in such cases.

The speaker discusses the role of acute phase proteins in the inflammatory response, noting their increase in response to cytokines and their systemic effects. The paragraph differentiates between positive and negative acute phase proteins, with albumin being a key negative acute phase protein. The discussion includes the impact of inflammation on thyroid hormone levels and the use of C-reactive protein as a more sensitive marker of inflammation.

This paragraph explores the balance of calcium and phosphorus in the body, the role of vitamin D and PTH in calcium regulation, and the impact of various conditions on calcium levels. The speaker discusses hypercalcemia and hypocalcemia, their causes, and the clinical signs associated with these conditions. The paragraph also addresses the treatment considerations for hypercalcemia, especially in the context of kidney function and the potential for soft tissue mineralization.

The speaker discusses how certain medications, such as those used for psoriasis, can affect calcium levels, leading to hypocalcemia. The paragraph also touches on the potential for granulomatous diseases to cause hypercalcemia due to macrophage production of vitamin D. The discussion includes the impact of various types of cancer on calcium levels and the importance of considering the speed of onset of hypercalcemia in assessing clinical severity.

This section delves into the clinical signs associated with imbalances in calcium levels, such as muscle weakness, constipation, and vomiting. The speaker discusses the importance of considering the speed of onset of hypercalcemia and its impact on the severity of clinical signs. The paragraph also addresses the use of EKG in detecting arrhythmias associated with calcium imbalance and the potential for hypocalcemia to be a negative prognostic indicator in certain conditions.

The speaker discusses various conditions that affect calcium regulation in pets, such as hyperparathyroidism and hypoparathyroidism, and their effects on ionized calcium levels. The paragraph covers the presentation of these conditions, their diagnosis through PTH levels, and the importance of preoperative management with calcitriol. The discussion also includes the potential for hypocalcemia to be asymptomatic and the importance of considering the ileum's role in calcium absorption.

This section addresses the emergency management of potassium imbalances, such as hyperkalemia and hypokalemia, which are commonly seen in conditions like Addison's disease and DKA. The speaker discusses the life-threatening nature of hyperkalemia and the importance of prompt treatment with insulin and dextrose. The paragraph also covers the management of hypokalemia, especially in the context of insulin therapy and the potential for potassium levels to drop rapidly.