What Is Multiple Sclerosis?
It is an inflammatory disorder affecting the central nervous system. Multiple sclerosis stimulates the immune system to attack the protective material (myelin sheath) surrounding the nerve cells, resulting in damage. It is a leading cause of neurological disability in young adults. The clinical presentation of individuals with the disease is pain, numbness, tingling sensation, blurry vision, dizziness, fatigue, weakness, tremors, and bladder dysfunction. Over 90 percent of individuals with multiple sclerosis manifest renal symptoms. Problems with the bladder are not constant and flare up on certain occasions. Rarely, the bladder issues can induce renal damage. Renal manifestations in multiple sclerosis are the leading sequelae causing social disability.
What Causes Renal Diseases in Multiple Sclerosis Patients?
The primary cause is antibiotics, which lead to the development of drug-associated nephropathy (kidney disease). Individuals can develop acute tubulointerstitial nephritis (injury to renal tubules and interstitium) by drug-induced immunologic processes or direct action caused by drug accumulation. Patients with multiple sclerosis undergo chemotherapy, which also causes renal damage. Patients undergoing hematopoietic stem cell transplantation receive chemotherapy, resulting in the development of complications like nephrotoxicity.
Renal side effects are induced by innate drug toxicity and several patient-related factors. The use of immunosuppressive drugs before transplantation may impair renal function before the procedure begins. Also, graft conditioning with Cyclophosphamide may further induce renal damage as kidneys are the main pathway for eliminating chemotherapy drugs and their metabolites.
What Are the Renal Effects of Multiple Sclerosis?
The renal effects induced by multiple sclerosis are:
Compromised glomerular filtration rate.
Urinary tract infections.
Bladder storage problems.
Bladder emptying problems.
Combined urinary emptying and storage problems.
1. Glomerular Filtration Rate
The glomerular filtration rate (GFR) is affected in patients with multiple sclerosis and indicates renal damage. Such patients may develop renal failure attributed to the neurogenic bladder (bladder malfunction), acute tubular necrosis (death of tubular epithelial cells), iatrogenic reduction in renal perfusion, or allergic interstitial nephritis. Many drugs that treat multiple sclerosis have the potential to induce infections. Hence, antibiotic therapy is needed.
2. Urinary Tract Infection
Nervous system lesions develop in multiple sclerosis patients, causing urine retention and sphincter dysfunction. Urinary continence is a regular feature in patients, and they need to use catheters to empty their bladders. On their own, urine retention and sphincter dysfunction can cause the development of infection, but with catheter use, the risk of developing and spreading infections is even higher. The urine retained in the bladder enables bacteria to grow, causing bladder infections. Urinary tract infections can further spread to the kidneys, which could result in severe complications like kidney failure. Urinary tract infections tend to occur if bladder emptying problems are untreated. The risk of developing urinary tract infection was two-fold higher in patients with multiple sclerosis. There is also a risk of mortality.
Renal disorders further complicate multiple sclerosis. When viral infection-induced urinary tract infection spreads to the kidneys, it can cause viral disease within the kidney. The body recognizes them as viral infections and initiates reactions inducing flare-ups of multiple sclerosis.
The symptoms of urinary tract infection include the urge to urinate, frequent urination, burning sensation while urinating, lower abdomen or back pain, fever, and unusual smelling dark urine. Multiple sclerosis patients must seek treatment for urinary tract or kidney infections to prevent unpleasant complications.
3. Renal Stones
Multiple sclerosis patients commonly develop calcium phosphate and struvite stones, but less likely calcium oxalate monohydrate stones. The method of bladder emptying was associated with the risk of kidney stone development. Individuals using intermittent straight catheterization (insertion or removal of catheter several times) are 3.5 times more likely to get stone disease, and those using indwelling catheters (collects urine in drainage bag) are ten times more likely to get kidney stones. Multiple sclerosis patients are likely to have had surgery to remove renal stones or percutaneous nephrolithotomy (a minimally invasive procedure for kidney stone removal).
4. Bladder Storage Issues
Dysfunction in bladder storage is a sign of an overactive bladder. The bladder tends to contract more than usual due to nerve damage. The contraction increases the urge in the affected individual to urinate more frequently. They may have to wake up several times at night to urinate.
5. Bladder Emptying Problem
The urinary bladder may not empty when the individual urinates. Nerve damage may cause interruption to the signals that help vacate the bladder. Causing the bladder to never empty or resulting in its overfill. Such individuals may have a weak urinary stream, incontinence, or urinary tract infections. The patients feel the urge to urinate but are hesitant when trying to urinate.
6. Combined Urinary Emptying and Storage Problems
Multiple sclerosis patients can have both bladder emptying and storage problems simultaneously. The condition is caused when the bladder muscle and urinary sphincter fail to coordinate. Individuals exhibit symptoms of both bladder storage and draining problems. The condition could also induce kidney damage.
Glomerulonephritis in multiple sclerosis patients is attributed to immunomodulatory therapies like interferon beta. The therapy is a first-line treatment in patients with relapsing and remitting multiple sclerosis. There are reports of minimal change in disease and membranous glomerulonephritis in patients taking interferon beta for multiple sclerosis. The kidney damage induced by interferon beta can be direct or indirect.
What Are the Measures to Overcome Renal Diseases in Multiple Sclerosis?
Lifestyle changes like limiting fluid intake at night, exercises to strengthen the pelvic floor, and bladder training may help better manage renal manifestation in multiple sclerosis patients. Multiple sclerosis patients must schedule bathroom breaks throughout the day. Avoid bladder irritants like cigarettes, caffeine, artificial sweeteners, and alcohol. If the renal symptoms do not resolve with lifestyle changes, the doctor may prescribe medications that control bladder contraction and decrease urine sensation. Bladder emptying dysfunctions are treated with catheters to enable complete bladder emptying.
Urinary tract infections in multiple sclerosis patients should be treated promptly. The first line of treatment for urinary infections is antibiotics. Patients with small renal stones are given medications to pass them through urine. Surgical options with catheter placement are advised if the renal stones do not clear. Using intermittent straight catheters, suprapubic tubes, or Foley catheters should be delayed wherever possible. The kidney excretes drugs for treating multiple sclerosis through glomerular filtration and tubular secretion. GFR helps eliminate non-protein-bound molecules, whereas proximal tubules excrete protein-bound molecules. Multiple sclerosis patients are known to have impaired renal function. Therefore, the doses of Cyclophosphamide drugs are adjusted to minimize the renal damage.
Few studies were reporting the link between renal disease and multiple sclerosis. The renal diseases developing in multiple sclerosis patients are urinary tract infections, renal stones, bladder problems, and glomerulonephritis. Timely diagnosis and management of renal disease can prevent the disease progression.