Acidosis and alkalosis Flashcards
(12 cards)
Respiratory acidosis
CO2 not removed efficiently; high CO 2 levels
decreasing pH due to more carbonic acid being produced
caused by hypoventilation
Respiratory alkalosis
Too much CO2 removed
due to hyperventilation (usually)
Decrease in CO2 causes shift to produce fewer protons so pH rises
Metabolic Acidosis
Increase in nonvolatile acids (e.g sulfuric acid)
Reacts with bicarbonate reducing bicarbonate levels, leading to decrease in blood pH
Can occur if body looses too much base e.g diarrhoea
Metabolic alkalosis
Increase in nonvolatile bases, often due to loss of stomach acids (e.g vomiting)
Increase of conc of bicarbonate in body
Distal Renal Tubular Acidosis (dRTA / Type 1 RTA)
It is caused by failure of the alpha-intercalated cells in the cortical collecting duct to secrete protons (H⁺) into the urine.
These cells are visible in immunohistochemistry slides as green-stained cell
Problems arising from dRTA 1
he body attempts to buffer the chronic acidosis using bone minerals, especially phosphate, which causes:
Loss of calcium and phosphate from bones, leading to osteomalacia.
Increased calcium in the urine (hypercalciuria) due to mobilization of calcium from bone.
Since the alkaline urine is rich in calcium, there is an increased risk of:
Kidney stones (nephrolithiasis).
Kidney calcification (nephrocalcinosis).
There is also hypokalaemia because potassium is wasted in the urine.
This occurs as the body attempts to maintain electrical neutrality in the absence of normal proton excretion.
Causes
Genetic mutations in:
The apical proton pump (H⁺-ATPase).
The basolateral bicarbonate-chloride exchanger (AE1).
Carbonic anhydrase itself.
Autoimmune diseases, especially Sjogren’s syndrome, which affects epithelial tissues including the alpha-intercalated cells.
Tubulointerstitial nephritis, which involves inflammation of the kidney’s interstitial compartment.
Toxic exposure, particularly to substances like toluene found in glue (i.e., glue sniffing).
Proximal Renal Tubular Acidosis (pRTA / Type 2 RTA)
Proximal RTA is less common than distal RTA and is traditionally referred to as Type 2 RTA.
It is caused by dysfunction of the proximal tubular cells, which are highly energy-dependent and packed with mitochondria.
FANCONI SYNDROME
What appears in the urine of someone with Fanconi syndrome
Phosphate
Urate
Glucose
Amino acids
Low molecular weight proteins
Bicarbonate, which is the key feature in RTA.
LESS SEVERE ACIDOSIS
Causes of proximal RTA include:
Multiple myeloma, due to light chain damage to tubules.
Tenofovir and other mitochondrial toxins.
Tubulointerstitial nephritis, similar to that causing distal RTA.
Use of carbonic anhydrase inhibitors, such as:
Acetazolamide
Topiramate
Type 4 RTA
Refers to RTA associated with hypoaldosteronism or aldosterone resistance.
Normally, aldosterone promotes potassium excretion and H⁺ secretion, so low aldosterone levels result in:
Hyperkalaemia
Mild metabolic acidosis
Causes of type 4
Type 2 diabetes (most common)
Chronic kidney disease (CKD)
Use of medications like:
Calcineurin inhibitors (e.g., cyclosporine, tacrolimus)
NSAIDs
Heparin
Primary adrenal insufficiency, such as Addison’s disease
