Question

Physiology

☆Acid-base balance Normal plasma pH ranges from 7.35-7.45, changes in plasma pH may disturb metabolism and many body functions.

1- Describe in detail the role of the kidney in adjusting blood pH either in acidosis or alkalosis.

2- Differentiate between metabolic and respiratory acidosis and alkalosis.

3- Explain in full details the endocrinal causes of metabolic acidosis.

4- Formulate a case for a patient with metabolic acidosis demonstrating possible signs, symptoms and laboratory investigations.

5- Referring to five recent publication (2015-2020), explain the pathophysiology and treatment of diabetic ketoacidosis.

6- Construct 5 MCQ about Addison's disease

Answer 1

1- Role of Kidney in adjusting th blood pH.

In case of Respiratory acidosis, kidney compensate by decreasing the Bicarbonate excreation and hence try to bring the pH up near to normal.

In case of Respiratory alkalosis, kidney compensate by increasing the bicarbonate excretion and hence try to bring pH down near normal.

2.

	Meabolic	Respiratory
Acidosis	It is due to increased H+ in the body due to decreased renal excretion of H+ or incresed excretion of HCO3-. Or any other metabolic cause leading to acidosis other than respiratory cause.	It is due to increased carbon dioxide accumulation in the blood due to inability of lungs to expirate CO2 out.
Alkalosis	It is due to increased bicarbonate in the blood either due to increased bicarbonate production or decreased bicarbonate excretion.	It is due to decreased carbon dioxide in the blood due to excessive wash out of CO2 by the process of respiration.

3. Endocrinal causes of metabolic acidosis includes

- Diabetic Keto-acidosis

- Adrenal Insufficency

In diabetic ketoacidosis - Due to decreased insulin lever there is decresed glucose utilisation by the cells, & In liver the fatty acid metabolism increases and leads to ketone body formation. Increased glucose in blood also leads to osmotic diuresis. Hence, both combination of osmotic diuresis and incresed Ketone body formation are responsible for acidosis in DKA.

In adrenal Insufficency - due to decreased aldosterone, the secretion of H+ and K+ decreses in the DCT and CD. Hence, increased H+ & K+ in the blood leads to, Hyperkalemia and Metabolic acidosis in Adrenal Insufficency.

4. A 7 year old male child came to the ER with altered sensosrium, lethargy and child is hyperventilating, child also had fruity odour in his breath and urine. There is history of diabetes in the mother and father. ABG done was suggestive of pH of 7.1, HCO3 - 13, pCO2 - 24, Urine and serum ketones were positive.

Solution key - DKA is most common first presentation in the child with Diabetes mallitus.