Acidosis is any condition where H+ ions are increased or where HCO- is reduced.

Hence, metabolic acidosis is a condition where hydrogen ions are more in plasma and bicarbonate ions are reduced.

It generally shows an increased anion gap, Delta- Delta gap.

Causes of metabolic acidosis.

• The agents which cause increased anion gap are increased production of organic acids, an overdose of medication, poisoning
• Excessive generation of lactic acid in the body.
• Renal failure, chronic Kidney disease.
• Direct Loss of ions from the body.

Causes for metabolic acidosis in detail:

• Severe renal failure: kidneys are the major organs along with lungs and skin secondary to maintain proper acid and base balance in the body. If bicarbonate absorption and hydrogen excretion do not occur sufficiently and smoothly it will lead to an imbalance of acid and base. Hence, when the kidney does not work to its optimal level, the proximal convoluted tubule and distal convoluted tubule do not absorb or release ions adequately. Also, the fluid volume, secretion of aldosterone, etc play an important role. Therefore this leads to metabolic acidosis In patients with renal failure and chronic Kidney disease.
• Excessive generation of organic acids: This occurs in patients with diabetes. Diabetic ketoacidosis is a complication of diabetes that further leads to metabolic acidosis. Other causes are ketosis which occurs due to alcoholism, hunger, or starvation.
• Poisoning: overdose of medication like glycol, another heavy metal poisoning like cyanide.
• Excessive lactic acid generation: in patients with arrhythmias, angina pectoris or heart attack, seizures, liver damage, gall bladder issue, hypovolemic shock, and septicemia excessive lactic acid leads to metabolic acidosis.
• Direct Loss: vomiting, diarrhoea, patient on diuretic tablets. Diuretics are the group of medications that increases the urine production and hence along with the body fluid bicarbonates are lost largely leading to metabolic acidosis.

How does the patient with metabolic acidosis present?

• Kussmaul’s breathing pattern. This is an abnormal breathing pattern that is characterised by deep sighing breathing. 
• Tachycardia or bradycardia.
• Low blood pressure
• Lethargic
• Fainting
• Giddiness
• Confusion
• Relatable history.

Three major findings in metabolic acidosis after investigation.

• The bicarbonate level in serum is reduced.
• The partial pressure of carbon dioxide is reduced
• the pH of the blood is reduced.

What is the treatment line in patients with metabolic acidosis?

• The cause has to be found out in order to reduce this complication.
• If the patient is on diuretics like spironolactone which is a potassium sparing diuretic, it can be replaced by other medication if that is the cause.
• As bicarbonates are reduced in the serum, infusion of bicarbonates into the blood is another way of management especially used in severe cases of metabolic acidosis.
• If the patient has any kidney issues with high severity then dialysis may be required.
• Proper education on diet, lifestyle modification, and management of the comorbid condition is the best treatment.
• Appropriate water intake has to be monitored.
• Patient counselling plays an important role.

How to prevent the recurrence or how to prevent metabolic acidosis?

• In patients with diabetes mellitus, patients should consume the medication to control glucose levels in the blood regularly. Frequent food intake and water intake have to be monitored. Avoiding diabetes ketoacidosis will itself prevent metabolic acidosis.
• In alcoholics: alcohol is a bad agent for the liver and kidneys. Consistent and long time use of alcohol leads to alcoholic ketoacidosis. Hence, alcohol consumption should be stopped immediately.
• Poverty: starvation leads to excessive hydrogen ions and reduced bicarbonates in the blood leading to this condition. Proper education, employment, and other governmental policies are required to stop this cause of metabolic acidosis.
• Exposure: avoid exposure to salicylates, carbon monoxide, etc. This can be done by switching jobs, changing the residence, or simply staying away from the source of poisoning.

Complications of metabolic acidosis.

• Paediatric population: growth retardation, loss of concentration, convulsions, excessive sleep, increased susceptibility to infections, weakness, weak musculoskeletal system.
• It can lead to diabetes mellitus in patients who are not diabetic.
• Hormonal imbalance.
• Osteoporosis, pathological fractures.
• Lethargy and loss of muscle mass.
• Liver damage.
• Kidney failure.
• Multiorgan abnormalities.
• It may be life threatening if left untreated.

Who are at risk of developing metabolic acidosis.

• The patient who has another acidosis like renal tubular acidosis, or respiratory acidosis.
• Pre and post surgery
• Alcoholic patient
• The patient who smokes a cigarette
• Drug abusers
• Patients with a pre existing renal disease like a failure, chronic Kidney disease
• Uncontrolled diabetes
• Uncontrolled hypertension.
• High salt intake
• Excessive consumption of meat.

What to bring to the notice of your nephrologist?

• If a person is Gasping for breath.
• If the patient is on any antihypertensive medications.
• Alcohol, tobacco consumption history
• Surgical history.
• Kidney abnormalities if any.

Summary:

Metabolic acidosis is usually a secondary complication of any preexisting condition. It is caused due to more H+ and low HCT- levels in serum. It can be caused due to direct loss of ions, increased anion gap, cardiac condition, liver issues, kidney issues, etc. 

It is characterised by low levels of pH, bicarbonates, and partial CO2 pressure. It is treatable by treating the underlying cause, bicarbonate infusion, etc.

Alcohol, tobacco, and starvation are the modifiable causes and Risk factors that can be changed to avoid metabolic acidosis.

It leads to diabetes, growth retardation, lethargy, atrophy, or even death.