Distal renal tubular acidosis
Renal tubular acidosis or RTA is a term that defines a type of disorder where the body’s acid levels are not properly maintained. In type 1 RTA, the distal tubule is the source of why the acid levels are imbalanced. Distal renal tubular acidosis is a condition that occurs when acids are not properly filtered from the bloodstream. It may also be referred to as dRTA, distal acidosis, renal tubular acidosis type 1, or classical RTA.
Definition & Facts
Distal renal tubular acidosis can occur because of an inherited genetic disorder, as a primary condition, or as a symptom of a disease or other medical problem. Resolving distal renal tubular acidosis requires treating any underlying conditions, removing acid from the blood, and restoring the body’s pH balance. Although distal renal tubular acidosis is often asymptomatic, it does require medical treatment to prevent serious and even life-threatening complications.
Symptoms & Complaints
Although it may not cause symptoms or those it may cause can be considered mild to moderate, the condition can become life-threatening. If symptoms do appear, they are similar to those of kidney disease or of a potassium deficiency. Some of the more common symptoms and complaints of distal renal tubular acidosis include:
- Muscle weakness
- Muscle trembling
- Extreme lethargy or fatigue
- Hyporeflexia or lack of reflexes
- Irregular heart rhythm
- Growth retardation
- Nephrolithiasis or kidney stones
- Nephrocalcinosis or too much calcium in the kidneys
- Hypokalemia or low potassium
- Bone disease
Distal renal tubular acidosis can be caused by a variety of different factors. The issue may be hereditary and caused by inherited abnormal genes that affect kidney or distal tubule structure and function. It can also occur when genetic or medical conditions affect certain bodily functions. Aldosterone deficiency, abnormal anion-exchange, or abnormal calcium build-up may lead to distal renal tubular acidosis.
When these conditions occur, it can set the stage for an imbalance in urine pH, which is the most common issue associated with dRTA. It is also possible for distal acidosis to occur as a side effect of certain medications. It can occur as a side effect of medications like amphotericin B, ifosfamide, and lithium among others.
One very common cause of distal renal tubular acidosis is complications associated with kidney transplantation, including organ rejection. Certain autoimmune diseases and chronic conditions like hepatitis, lupus, chronic urinary tract infections, kidney disease, and chronic obstructive uropathy may lead to this disorder. Additionally, type 1 tubular acidosis may result from the following:
- Sickle-cell anemia
- Sjögren’s syndrome
- Thyroid disorders
- Cacchi-Ricci disease (medullary sponge disease)
Diagnosis & Tests
Diagnosing distal renal tubular acidosis will require both blood tests and clinical urine tests for lab testing, a complete physical examination, and other tests if needed. Urine pH tests are the most common diagnostic test used to identify dRTA. Although it can help identify the state of acidosis, further testing is necessary to identify if it is dRTA or another form of renal acidosis.
A complete urinalysis will also be completed on the urine sample. This will help look for potential causes and clearly identify the levels of various electrolytes and compounds like sodium, potassium, calcium, and chloride. These levels can help identify which treatment methods will be most effective at restoring balance to the system. Blood work will also help confirm dRTA. Arterial blood gas and a full blood chemistry profile can help identify the problem and often its underlying cause.
Medical staff may pursue an acid loading test to help compare acid levels and determine if renal acidosis is present. Testing will also look to identify the underlying cause of the condition and look for signs of infection, disease, or other medical conditions. In some cases, diagnostic imaging techniques may be used to look at the kidneys and surrounding structures. This could include X-rays or ultrasounds.
Treatment & Therapy
Once distal renal tubular acidosis has been diagnosed, treatments will be prescribed to restore pH level and electrolyte balance. This is generally accomplished using either oral or intravenous (IV) methods. Medical staff will provide electrolytes via IV fluids to restore balance and prevent dehydration.
Additionally, medications like alkaline medicines, sodium bicarbonate, potassium citrate, or sodium citrate may be prescribed. In some cases, supplements like vitamin D and calcium may also be recommended. These treatments along with regular testing of acid levels should improve the body’s pH balance. Additional therapies may be needed to treat the underlying cause of dRTA and prevent its recurrence.
Prevention & Prophylaxis
Be sure to follow any directions provided by your medical professional, including the proper dosing of all prescribed medications and supplements. Seek medical attention if symptoms worsen, or if weakness, seizures, or disorientation occur.