A condition in which a person has too much acid in the blood, caused by a kidney problem, is called renal tubular acidosis (RTA). In general, there are 3 types of this disorder. While some people may develop it due to some medicines, others may experience it due to autoimmune or genetic disorders. In most cases, doctors treat RTA with medications that help reduce pH levels.
In other words, this condition occurs when the kidneys are unable to remove excessive acid and other waste products from the blood. In general, the kidneys have multiple jobs, including regulating the body’s pH. Thus, the body pH measures the levels of acids and bases in the body, which are very important for the body to function properly. If the pH levels range between 7.35 and 7.45, it is considered normal. If the pH level drops below the previous range, it is acidic, and if it increases more, it is basic.
For instance, when a person eats a meal that contains a lot of protein, the body will make a lot of acids. Thereafter, the kidneys should get rid of these excess acids to maintain a normal level of pH in the body. However, when people eat meals that with a lot of vegetables and fruits, the body has a lot of bases.
When the levels of pH in the body increase, it may affect multiple systems in the body (such as breathing). In severe cases, renal tubular acidosis can be fatal without immediate treatment.
Nowadays, studies about this disorder are ongoing. That’s why this disorder is frequently misdiagnosed or underdiagnosed. In such cases, it is quite difficult to estimate how many people have this disorder.
Types of Renal Tubular Acidosis
Experts have divided this disorder into several types according to the affected part of the renal tubule. For example:
- Distal RTA or dRTA (type 1) – In such cases, damage occurs to the (distal) far parts of the kidney tubules.
- Proximal RTA or pRTA (type 2) – This type of renal tubular acidosis affects the proximal (closer) part of the kidney tubules. It occurs rarer than the previous type of RTA and is often related to alcohol use disorder, multiple myeloma, or other genetic disorders.
- Distal and Proximal RTA (type 3) – This is a type of RTA that impacts both the distal and proximal parts of the kidney tubules. However, it occurs very rarely, and doctors usually do not use it to classify RTA.
- Hyperkalemic RTA (type 4) – This type of disorder affects the end part of the kidney tubules, and the kidneys cannot get rid of enough Potassium (hyperkalemia) and acid. Moreover, this condition also affects the kidney’s ability to filter acid from the blood. In addition, hyperkalemic RTA is the most common type of renal tubular acidosis, and it often occurs if you have diabetes or take some medicines.
Symptoms
People with RTA often experience symptoms due to increased acid levels in the body. It negatively affects multiple organs and systems in the body. Check below some common symptoms:
- Bone pain
- Tachypnea (fast breathing)
- Confusion
- Dehydration
- Fatigue (extreme tiredness)
- Tachycardia (increased heart rate)
- Arrhythmia (irregular heart rhythm)
- Muscle weakness
- Pain in the back, flank, or abdomen (belly)
- Oliguria (reduced urination)
- Osteomalacia (weakening and softening of bones)
If you notice any of the previous symptoms, it is advised to see a healthcare professional right away. It is vital to get immediate treatment if you have RTA. Otherwise, it may lead to permanent damage or even death.
Causes
The causes depend on which type of RTA you develop. Check below some examples:
Type 1 RTA
Usually, people with this type of RTA inherit it from a biological parent. However, you may also develop it due to an autoimmune disorder or some medicines. For example:
- Autoimmune disorders – These include Sjogren’s syndrome, systemic lupus erythematosus (lupus), rheumatoid arthritis (RA), and others.
- Genetic disorders – In normal circumstances, the following genes balance the acids and bases in the body. If you develop mutations (changes) in any of the following genes, it may lead to type 1 RTA. For example, SLC4A1, ATP6V0A4, and AT6V1B1.
- Medicines – The following medicines may cause type 1 RTA. Examples include antifungals (such as Amphotericin B), antipsychotics (including Lithium), and antibiotics (such as Pentamidine).
In most cases, adults develop type 1 RTA due to autoimmune disorders.
Type 2 RTA
Generally, there are multiple reasons that may cause this type of RTA. These include genetic disorders and medicines. For example:
- Amyloidosis
- Hereditary fructose (fruit sugar) intolerance
- Multiple myeloma
- Cystinosis
- Fanconi syndrome
- Wilson’s disease
- Light chain monoclonal gammopathy of renal significance
Moreover, there are some medications that may also cause type 2 RTA. These include medicines used to treat the following health conditions. For example:
- HIV infection
- Migraines
- Glaucoma
- Seizures
- Viral hepatitis
In addition, prolonged exposure to heavy metals (such as Lead and Cadmium) may also cause type 2 RTA. The most common causes of this type of RTA in adults include amyloidosis, multiple myeloma, and light chain monoclonal gammopathy of renal significance.
Type 4 RTA
While this type can occur due to an inherited disorder, it may also happen due to an acquired condition that negatively affects the kidneys. For example:
- Diabetes-related nephropathy
- HIV/AIDS
- Kidney transplant rejection
- Lupus
- Sickle cell disease
- Addison’s disease
- Urinary system obstruction (including benign prostatic hyperplasia, kidney stones, or tumors)
- Gordon’s syndrome
- Amyloidosis
This type of RTA may also occur due to reduced Aldosterone levels. This is a hormone that helps the kidneys regulate the Sodium (salt) levels in the body. In addition, some people may develop type 4 RTA due to some medications. Examples include:
- Blood thinners (also called anticoagulants)
- Immunosuppressants (medicines often used to prevent organ transplant rejection)
- Diuretics
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Antibiotics
- Blood pressure medicines (including ARBs and ACE inhibitors)
One of the most common causes of type 4 RTA in adults is diabetes-related nephropathy.
Risk Factors
Healthcare professionals have identified some factors that could increase your risk of developing RTA. Check some of them below:
- Blockages in the urinary system
- Autoimmune disorders (such as Fanconi syndrome, lupus, or Sjogren’s syndrome)
- Long-term exposure to Cadmium or Lead
- Abnormal inherited genes from biological parents
- Receive a kidney transplant
- Some medicines (such as immunosuppressants)
What Are The Possible Complications of Renal Tubular Acidosis?
Those who develop RTA may also experience some complications. However, people usually experience different complications because it depends on the type and severity of RTA they develop. Check below some examples:
Type 1 RTA Complications
- Calcium buildup in the kidneys (it may also lead to kidney stones)
- Growth faltering (growth delayed in children)
- Deafness (hearing loss)
- Sickle cell anemia
- UTIs (urinary tract infections)
- Ehlers-Danlos syndrome (weak connective tissues)
- Chronic kidney disease (CKD)
- Metabolic bone disease
Type 2 RTA Complications
- Delayed growth and development in children
- Dental problems
- Soft bones
Type 4 RTA Complications
- Cardiac arrest (that is often caused by increased Potassium levels in the blood)
- Muscle weakness
- Arrhythmia (irregular heart rhythm)
This article does not contain a complete list of RTA complications. However, you can consult with your healthcare provider about ways to reduce the risk or prevent previous complications.
Diagnosis
Usually, it is challenging to diagnose this condition. Doctors often begin with a physical examination to check for irregularities linked to the disease and an evaluation of your medical history. They may also ask some questions about the symptoms and perform some tests to rule out disorders that cause similar symptoms. These include blood tests to measure pH levels in the blood and urinalysis (urine tests).
Treatment
The treatment for people with this condition is often different because it depends on several factors. For example, the type and severity of the condition, overall health, age, and preferences. In general, doctors recommend oral alkali therapy (Sodium bicarbonate or Sodium citrate) for all types of RTA. This treatment helps increase blood pH, ease the symptoms, and prevent certain serious health conditions (including kidney stones or failure, bone diseases, and others).
In most cases, the forms of alkali therapy are tablets, but they may also include a solution that should be drunk. In addition, your healthcare professional may also recommend the following medicines and supplements to improve the effectiveness of the primary treatment. Examples include:
- Calcium and vitamin D supplements
- Potassium citrate replacement
- Thiazide diuretics (including Hydrochlorothiazide or Chlorthalidone)
- Dietary changes
Frequently Asked Questions
What is the main cause of renal tubular acidosis?
The most common causes include autoimmune disorders (such as Sjogren’s syndrome or lupus), genetic disorders, certain medications, and some diseases (including diabetes, urinary tract obstruction, and others). For more details, discuss it with your doctor.
What medications can cause RTA?
In most cases, people who take the following medicines develop RTA. For example, Ifosfamide, Oxaplatin, Aminoglycosides, Tenofovir, Cidofovir, Adefovir, Didanosine, Topiramate, Valproic acid, and others. Do not hesitate to visit a doctor if you think the medicines you are administering increase your risk of developing RTA.
What is the most common organ injured in RTA?
Usually, this disorder causes damage to the liver and spleen. It means that the liver and spleen are more commonly affected by RTA than other organs. Ask your healthcare provider if you have additional questions.
