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Discussion Topic #4: Respiratory & Renal
Acid-Base Homeostasis: Type 1 Diabetes Patient Case Study
Part 1: Oregon State University Anatomy & Physiology Course – 26.4: Acid-Base Balance (Links to an external site.)
The link above is required reading using Oregon State University’s open source textbook for their Anatomy & Physiology course. This is a supplement to the acid-base regulation lecture discussions in Chapters 13 & 14 of our course.
The key here is that you have two systems, respiratory and renal, working together to address situations where acid/base homeostasis is disturbed.
Part 2: Clinical Case Study – Diabetic ketoacidosis
Read the case summary below and then answer the questions that follow.
Case: During your shift in the ER, a 21-year old noncompliant male with a history of type I (insulin-dependent) diabetes mellitus was found in a coma. Your triage assessment and the lab testing revealed the following:
- Hyperglycemia: High blood glucose.
- High urine glucose.
- High urine ketones and serum ketones.
- Low serum bicarbonate <12 mEq/L.
- Exaggerated respiration.
- Breath has acetone odor.
- Hypotensive: blood pressure was 90/60 mm Hg.
- Tachycardia: Pulse weak and rapid (120 bpm).
Based on your understanding of both the respiratory and renal regulation of blood pH, answer the following:
- Is this patient experiencing respiratory or metabolic acidosis? Why?
- How does the following formula represent the respiratory & renal systems’ regulation of acid-base balance (remember that the enzyme carbonic anhydrase catalyzes the forward reaction between carbon dioxide and water):
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–
Discussion Topic #4: Respiratory & Renal Answer
1.) The classification of an acid-base disorder is dependent on the clinical presentation of the disorder in the patient, and for this case, the patient is experiencing metabolic acidosis. A high blood and urine glucose content indicates that glucose is not being absorbed by the body, and is therefore excreted. At the same time, the high urine and serum content indicates that the body has undergone ketolysis, wherein ketone bodies are converted to acetyl-CoA due to the lack of energy source, causing a decrease in the acidity of blood (acidosis).