RTA is a medical condition that disrupts kidney operations in acid-base balance control. The kidneys sustain body acidity levels and remove waste through a filtering process to keep blood pH within the correct range. But, when kidney tubules does not perform their function correctly, excess acid accumulates in the body, leading to metabolic acidosis.

Three main sources of this medical condition include genetic disorders, autoimmune diseases or problems with the kidneys. The prevention of bone loss, kidney stones and problems affecting child growth depends on an early diagnosis and a proper treatment approach.

This article discusses several renal tubular acidosis types, their origin factors, diagnostic approaches, and treatment options.

What is Renal Tubular Acidosis?

The body's acid-base balance is critical for normal physiological functions. The kidneys help regulate this balance by reabsorbing bicarbonate (HCO₃⁻) and excreting hydrogen ions (H⁺) through the urine. When these processes are disrupted, excess acid builds up in the blood, leading to renal tubular acidosis.

The primary role of the kidney tubules is to:

• Filter out waste and excess substances from the blood
• Reabsorb essential nutrients and electrolytes
• Regulate pH levels by controlling acid and base excretion

In RTA, this regulation is impaired, leading to a drop in blood pH, which can negatively impact various organs and metabolic processes.

Types of Renal Tubular Acidosis

There are different renal tubular acidosis types, each with distinct causes, symptoms, and underlying mechanisms.

Distal Renal Tubular Acidosis (Type 1 RTA)

Failure of efficient hydrogen ion excretion by distal renal tubules leads to the development of distal renal tubular acidosis. When acid cannot be eliminated from the blood properly the amount in circulation increases while urine turns excessively alkaline.

Causes of Type 1 RTA

• Autoimmune disorders such as Sjögren’s syndrome and lupus
• Genetic mutations that affect acid excretion
• Kidney diseases like obstructive uropathy
• Chronic urinary tract infections that damage kidney tubules
• Certain medications, including lithium and amphotericin B

Symptoms of Type 1 RTA

• Chronic fatigue and muscle weakness
• Bone pain and increased risk of fractures
• Growth retardation in children
• Recurrent kidney stones due to high calcium excretion
• Excessive urination and dehydration

Proximal Renal Tubular Acidosis (Type 2 RTA)

Proximal RTA causes tubule cells to have reduced efficiency when reabsorbing bicarbonate amounts from urine. The body struggles to keep normal pH levels because bicarbonate escapes excessively through urine in this condition

Causes of Type 2 RTA

• Genetic disorders such as Fanconi syndrome
• Heavy metal poisoning, including lead and mercury exposure
• Multiple myeloma, which affects kidney function
• Vitamin D deficiency leading to bone demineralization
• Certain medications, including acetazolamide

Symptoms of Type 2 RTA

• Weakness and muscle pain
• Softening of bones (osteomalacia) and rickets in children
• Increased calcium loss, leading to kidney stone formation
• Dehydration due to excessive bicarbonate loss

Type 4 Renal Tubular Acidosis (Hyperkalemic RTA)

Renal tubular acidosis type 4 is different from other types. It is associated with increased potassium levels through hyperkalemia. The condition stems from deficient hydrogen and potassium ion secretion. It is related to aldosterone deficiency or resistance.

Causes of Type 4 RTA

• Diabetic nephropathy causing kidney damage
• Adrenal insufficiency, leading to low aldosterone levels
• Medications, including ACE inhibitors and potassium-sparing diuretics
• Chronic kidney disease (CKD). This affect electrolyte balance

Symptoms of Type 4 RTA

• Muscle weakness and irregular heartbeats due to high potassium levels
• Fatigue and difficulty concentrating
• Numbness and tingling in extremities
• Reduced urine production in severe cases

Causes of Renal Tubular Acidosis

The causes of RTA vary depending on its type and whether it is inherited or acquired. The most common causes include:

• The autoimmune diseases lupus and Sjögren’s syndrome destroy renal tissue which results in acid buildup in the body.
• People who inherit RTA typically develop symptoms during childhood because of their genetic disorder.
• Any of these three conditions are Chronic infections, urinary tract obstructions, or CKD that lead to RTA development.
• The kidney function of patients becomes affected due to the presence of specific medications and toxic substances.
• Diseases which interfere with mineral metabolism create difficulties in acid elimination through the urinary system.

Symptoms of Renal Tubular Acidosis

The renal tubular acidosis symptoms vary depending on the severity and type of the condition. Some of the common symptoms include:

• General Symptoms
  • Persistent fatigue and muscle weakness
  • Poor growth in children
  • Dehydration and frequent urination
• Bone and Kidney Symptoms
  • Bone pain and softening (osteomalacia)
  • Increased risk of kidney stones
• Electrolyte Imbalance Symptoms
  • Muscle cramps and irregular heartbeats (common in Type 4 RTA)
  • Numbness and tingling sensations in hands and feet

Diagnosis of Renal Tubular Acidosis

Doctors use several tests to diagnose RTA:

1. Blood Tests – Check blood pH and bicarbonate levels
2. Urine Tests – Analyze urine pH and acid excretion
3. Electrolyte Panel – Measure sodium, potassium, and chloride levels
4. Genetic Testing – Identify inherited forms of RTA

Imaging tests like ultrasound may be used to detect kidney stones or structural abnormalities.

Treatment of Renal Tubular Acidosis

Effective renal tubular acidosis treatment depends on the type and severity of the condition.

Alkali Therapy

Most patients receive sodium bicarbonate or potassium citrate to correct acidosis. These help neutralize excess acid and restore normal blood pH levels.

Potassium Management

• In Type 1 and Type 2 RTA, potassium supplements may be needed to correct low levels
• In Type 4 RTA, potassium-lowering medications such as diuretics may be prescribed

Treating Underlying Causes

• Autoimmune disorders: Medications like corticosteroids or immunosuppressants may be used
• Chronic kidney disease: Managing diabetes and blood pressure helps prevent further kidney damage
• Medication Adjustments: Stopping drugs that contribute to RTA is necessary for some patients

Complications of Untreated RTA

If renal tubular acidosis is left untreated, it can lead to severe health problems:

• Bone Weakness – Chronic acidosis depletes calcium, leading to fractures
• Kidney Stones – High calcium excretion increases stone formation
• Growth Issues – Children may experience delayed growth and short stature
• Electrolyte Imbalances – Severe potassium disturbances can lead to muscle paralysis or heart failure

Conclusion

Renal tubular acidosis is a serious condition that disrupts the body's acid-base balance, leading to various health problems.

For individuals experiencing persistent symptoms such as fatigue, muscle weakness, kidney stones, or electrolyte imbalances, consulting a nephrologist in Haryana is essential.

SS Kidney Urology Hospital provides specialized care for kidney disorders, including renal tubular acidosis. With expert urologists in Haryana, the hospital offers advanced diagnostic and treatment options to help patients manage kidney conditions effectively.