Staghorn Kidney Stones

What are staghorn kidney stones? 

Kidney stones consist of a build-up of chemicals and cellular substances (dissolved salts and minerals) from the urine. Most kidney stones are sizably small enough to be excreted during urination. Some stones may also reside in the kidneys and not cause any harm. However, larger stones can cause serious health problems. If the stone is large, it has the potential to be lodged in the ureter (a passageway of urine from the kidney to the bladder), blocking the flow of urine. In cases where the build-up, or kidney stone, encompasses a larger area, such as complete or partial spread in the renal pelvis and renal calyces, they are staghorn kidney stones.  

Staghorn kidney stones are an accumulation of struvite stones caused by infections in the upper urinary tract. They can present as physical symptoms such as frequent urination, increased urination, nausea, vomiting, painful urination, fever, chills, bloody urine, foul-smelling urine, discolouration in urine or other urine abnormalities.  

Debris remaining from a previous stone, or infection, can lead to kidney stone recurrence, even after active treatment. Associated with high morbidity and potential mortality, staghorn kidney stones require immediate attention, medical care and follow up care, and active assessment of our lives to be aware of the risk factors, causes and associations of this condition. The urgency can be attributed to the fact that, upon being left untreated, staghorn kidney stones can potentially induce renal deterioration via continual accumulation of staghorn stones, subsequently causing kidney destruction and failure and/or renal sepsis.  

Complete removal of the kidney stone is vital to prevent complete renal deterioration and kidney failure. It will additionally eradicate the infection, provide obstruction relief, prevent the growth of kidney stones, and preserve kidney function. The treatment ideally involves surgical removal of the staghorn kidney stones, described further in this article. 

Since surgical intervention may not be enough to completely eradicate the urease-producing bacteria, which increase urine pH and result in mineral crystallization, additional pharmaceutical therapy is necessary to prevent the recurrence of the stones. This is supplemented by follow up care, consisting of ultrasounds and/or x-ray scans to assess and investigate the presence of further stone development. This will ensure normal urinary system function. 

What are the causes of staghorn kidney stones? 

Staghorn kidney stones are caused by recurrent infections in the upper urinary tracts. They can also be caused by renal tract abnormalities, injuries to the spinal cord or neurogenic bladder. 

A neurogenic bladder refers to an abnormally functioning urinary bladder caused by injury to the nerves in the central and peripheral sections that regulate and control urination. The biological basis of staghorn kidney stone formation is associated with the presence of bacteria. Staghorn kidney stones are formed by struvite, referred to as struvite stones. Struvite stones are formed as a by-product when specific bacteria (Proteus and Klebsiella)  enter the body (in the form of infection) and break down the urea (a waste product produced by the body and a component of the urine) into ammonia. This by-product (struvite) is only produced when the urine has an alkaline environment. Urine turns alkaline in cases where an individual has urinary tract infections, thereby leading to the eventual formation of staghorn kidney stones. Additionally, ammonia can also make the urine more alkaline. 

What are the risk factors for staghorn kidney stones? 

The risk factors comprise of but are not limited to: 

Decreased Hydration

Low level water consumption results in dehydration. A lack of fluid intake can culminate in a homeostatic imbalance (imbalance of the body’s internal conditions), and subsequent kidney function impairment. This leads to the development of kidney stones. 

Reduced Urine Synthesis

Individuals with metabolic issues, systemic diseases associated with the kidneys, renal infections or urinary tract infections are more likely to have reduced urine production, culminating in calculi formation and the development of staghorn stones. 

Sex

People assigned female at birth, owing to anatomical susceptibility, are more likely to get urinary tract infections and are at a higher risk of developing struvite calculi and phosphate stones. People assigned male at birth are at greater risk of developing normal kidney stones. 

Systemic Disease and Infections

Most staghorn kidney stones are caused by persistent urinary tract infections left untreated. Additionally, chronic inflammatory conditions that cause immune reactions, such as bowel disease, diabetes, celiac disease, hormonal imbalances (hyperparathyroidism), high urine calcium, and surgeries such as gastric bypass surgery, can increase the risk of developing staghorn kidney stones.

Age

Anyone between the ages of 20-50 years of age has the potential to develop kidney stones. However, staghorn stones generally develop over the ages of 50.  

Diet

A mineral-rich diet of oxalates, phosphates, protein and salt can increase the likelihood of renal stone development. They can disturb the balance in the body, causing impaired renal functioning. 

Lifestyle

Individuals that lead a more sedentary and less active lifestyle, in addition to unhealthy eating habits, obesity and severe alcohol consumption, are likely to increase the risk of developing staghorn kidney stones and struvite kidney stones.

Medication

The administration of certain medications such as calcium- and magnesium-based antacids, phenytoin for epileptic seizures, potassium- and sodium-based diuretics for hypertension, can increase the risk of renal stone development, struvite stones and staghorn kidney stones.  

What are the complications associated with staghorn kidney stones?

Staghorn kidney stones can lead to the formation of several conditions, including chronic systemic inflammation adjunct to immune-mediated responses. It can lead to partial or complete kidney infection, causing tissue necrosis and organ failure. 

It can also cause azotaemia, an abnormality marked by the build-up of nitrogenous-based products and creatinine in the kidneys, usually caused by infections, leading to acute renal failure, loss of appetite, energy, vomiting and fluid retention. 

It can also cause hydronephrosis, the dilation of the kidney components due to partial or complete obstruction to the urine flow, causing bladder distention, renal colic, discomfort and pain.  

It is also associated with perinephric abscess formation due to urinary tract obstruction causing spread from infection sites, culminating in the accumulation of cells and debris. The kidneys, in such cases, are a place for infection growth where the bacteria clump to the stones and are resistant to antibiotic treatments. 

Xanthogranulomatous pyelonephritis is also a consequence of staghorn kidney disease, primarily caused by the bacteria Proteus. It is marked by chronic inflammation in the kidney due to destructive obstructions in the form of masses (stones) in the renal system. It can also affect structures and organs near the renal system.  

Sepsis is a dangerous complication of staghorn kidney stones. Septic shock can occur due to infections within the body. It is a life-threatening condition resulting from the overreaction of the immune system to an infection within the body, causing the body to damage its own components and organs.  

How are staghorn kidney stones treated? 

The treatment types include percutaneous nephrolithotomy (PNL), combinations of PNL and shock-wave lithotripsy (SWL), and medical management. Depending on several factors and histological features, a treatment modality or a combination of treatment modalities will be administered.  

Percutaneous nephrolithotomy

This minor surgery involves the extraction of calculi that cause unmanageable blockages via an incision in the back. It is the most preferred treatment option, boasting high stone-free rates (78%). Open surgery might be considered only in cases where staghorn kidney stones are extremely large. This option is also recommended in patients with skeletal abnormalities, chronic infections, morbid obesity and severe renal damage. This is coupled with treatment for infections.  

Some of the complications associated with PNL include, but are not limited to, sepsis, hemorrhage, colonic perforation, pneumothorax, vascular injury and perforation in the collecting urinary systems, acute kidney loss, hydrothorax, prolonged leaks and ureteral stones.  

Shock-wave lithotripsy

SWL is a non-invasive treatment where extracorporeal shock waves, via ultrasound imaging or fluoroscopy, are administered to patients for calculi and stone fragmentation. They can cause complications of steinstrasse (the build-up of stone fragments due to incomplete fragmentation post-SWL), renal hemorrhage, haematuria (bloody-urine), urinoma (fluid collection), acute kidney loss, renal colic, ureteral stones and renal impairment. The stone-free rate for SWL is significantly lower than PNL; however, a combination of both is usually more helpful. 

A sandwich therapy or combination therapy involves the reduction of the stone load using PNL, supplemented by SWL to fragment the stones that are difficult to access via an endoscope. This is followed by PNL, again, to remove any excess fragments.  

Pharmaceutical Management

Medical management involves the use of  urease inhibitors for the prevention of staghorn kidney stone formation. Antibiotic therapy can also be used to eradicate infections from remnant stone fragments. 

FAQs: 

• What is a staghorn stone in the kidney? 
  A staghorn stone in the kidney refers to a stone formed due to the build-up of struvite, culminating primarily from urinary tract infections, encompassing or spreading in the branches completely or partially in the renal calyces through the renal pelvis.  
• What is the cause of staghorn kidney stones? 
  Staghorn kidney disease is caused by a variety of known bacterial agents or microbial agents present due to a urinary tract infection in many individuals.  
• How is a staghorn kidney stone removed? 
  A combination of percutaneous nephrolithotomy, shock-wave lithotripsy and pharmaceutical management, coupled with follow-up care is effective in treating staghorn kidney stones. 
• Do staghorn calculi cause pain? 
  All kidney stones cause pain. Staghorn kidney stones are much larger, causing more pain and discomfort than smaller kidney stones.  
• How do you dissolve staghorn kidney stones? 
  Staghorn kidney stones are much larger in size and cannot be dissolved. They are caused by a build-up of a variety of chemicals. They can be thick and hard as a result of which, they will require surgical treatment in most cases.