Pathogenesis (disease development)
Metabolic acidosis is defined as a metabolic decrease in blood pH <7.36. Possible causes of metabolic acidosis include:
- Addition Acidosis and Subtraction Acidosis Metabolic acidosis can result either from increased metabolic uptake or production of acids (addition acidosis) or from increased losses of bases (HCO3; hydrogen carbonates, obsoletely also bicarbonates) (subtraction acidosis). During the degradation of dietary protein (protein), acid valencies, so-called “fixed” acids (sulfate and phosphate from sulfuric and basic amino acids) are formed, which the organism cannot “exhale”. These acids are urinary and are excreted by healthy kidneys – but in old age, they can overload the buffer system in the long term.
- Renal (belonging to the kidney) acidosis Renal acidosis occurs when the kidney is no longer able to excrete enough acids or increased excretion of bases (HCO3). A distinction is made between metabolic acidosis with a large or small anion gap. The anion – a negatively charged ion – is chloride. A small anion gap indicates organic causes, such as keto or lactic acidosis – acidosis caused by ketone bodies or lactate (lactic acid). The large anion gap indicates rather poisoning, for example, with alcohol.
Etiology (causes)
Biographical causes
- Genetic burden
- Genetic diseases
- Renal tubular acidosis (RTA) – genetic disorder with autosomal recessive inheritance that leads to a defect defect H+ ion secretion in the tubular system of the kidney and consequently to demineralization of bone (hypercalciuria and hyperphosphaturia/increased excretion of calcium and phosphate in the urine) and hypokalemia (potassium deficiency).
- Genetic diseases
Behavioral causes
- Nutrition
- Starvation state – increased acid production
- Overeating – increased acid production
Causes due to disease
- Gastrointestinal (gastrointestinal tract related:
- Diarrhea (diarrhea) – increased losses of HCO3.
- Ketoacidosis (diabetic (diabetic ketoacidosis, DKA), hunger, alcohol)Note: Approximately 6-7% of pregnant women suffer from diabetes mellitus (DM); this is about 90% of cases are gestational diabetes.
- Lactic acidosis:
- Renal (kidney related):
- Renal insufficiency (chronic renal impairment) → hyperkalemia (excess potassium).
- Renal tubular acidosis (RTA).
- Uremia (increased occurrence of urinary substances in the blood due to lack of or insufficient renal function) – due toreduced ability to adequately excrete daily dietary intake of acids with severely reduced glomerular filtration rate (GFR).
- Alcohol abuse (alcohol abuse)
- Diabetes mellitus
- Diarrhea (diarrhea) → gastrointestinal bicarbonate loss.
- Cachexia (emaciation; emaciation).
Medication
- ACE inhibitors – group of drugs used for hypertension (high blood pressure); this group includes mainly ramipril and captopril.
- AT1 antagonists (angiotensin II receptor subtype 1 antagonists, AT1 receptor antagonists, angiotensin receptor blockers, “sartans“) – group of drugs used in hypertension (high blood pressure); this group includes mainly valsartane.
- Acetazolamide – carbonic anhydrase inhibitor from the substance class of sulfonamides, which can lower eye, brain and blood pressure.
- Calcium chloride – drug, which is administered for potassium deficiency.
- Ciclosporin (cyclosporin A) (immunosuppressant).
- Colestyramine – drug used as a fat-lowering agent.
- Hippurate – drug which is used for urinary tract infections.
- Potassium-sparing diuretics – diuretic drugs such as amiloride or spironolactone.
- Cation exchange resins
- Magnesium sulfate – prescribed as therapy for magnesium deficiency or as an Epsom salt.
- Pentamidine (chemotherapeutic agent)
- Salicylates – group of active substances to which acetylsalicylic acid (ASA) belongs, used as an analgesic.
- Trimethoprim (antibiotic) – drug against bacterial infections.
Operations
- Ureterosigmoidostomy – transplantation of the ureter into the sigmoid colon, primarily to form a replacement bladder in bladder cancer (bladder cancer).
- Condition after surgery in which an external pancreatic or small intestinal drainage was created.
Environmental exposure – intoxications (poisonings).
- Alcohol
- Ethylene glucole – used as an antifreeze.
- Methanol
- Toluene