Be aware of kidney stones

Also known as renal calculi or urinary tract stones, their prevalence has increased rapidly in recent years as a result of a meat-heavy western diet and obesity. In many cases, kidney stones can be cured but recurrences are frequent and serious renal complications may occasionally occur.

Kidney stones are mainly made of calcium oxalate minerals that come from oxalate-rich foods such as chocolate and certain fruits and vegetables, for example. Other stones are made of calcium phosphate, uric acid (from a high-protein diet) and struvite (from repeated urinary tract infections). Size varies from small “gravel-like” deposits to stones measuring a centimetre. 

Predisposing factors include abnormal kidney anatomy, acquired or inherited metabolic disorders that increase the levels of some minerals and insufficient fluid intake that favours the concentration and subsequently the crystallisation of minerals. 

A kidney stone can often go undetected until it spontaneously moves from the kidney cavity to the urinary tract through the ureter, the thin tube connecting the kidney with the bladder. By abruptly interrupting the urine flow, the calculi stuck in the ureter induces high pressure up to the kidney leading to renal colic syndrome that typically presents as sudden excruciating pain in one flank radiating to the groin, testis or anterior thigh. Other symptoms may include agitation, anxiety, nausea and vomiting, difficulties in urination and presence of blood in the urine. The pain, which may last a few hours, may fluctuate in intensity when the stone moves down and finally disappears when the calculi is passed during urination. Kidney stones manifestations may often be mistaken for acute abdominal diseases (gallbladder stone, appendicitis, colon inflammation), spine problems or other kidney illnesses. A stone may also remain “silent” within the kidney for years and be discovered at a routine health check-up. Complications occur when the obstructing calculi severely impact the renal function resulting in acute renal failure or grave infection of the kidney. The presence of fever with symptoms suggestive of kidney stone is a medical emergency. 

Renal calculi are diagnosed through blood tests, urine analysis (to evaluate the presence calculi-forming substances) and imaging investigations such as ultrasound or CT scan of the abdomen. Importantly, any stone that is eliminated through the urine must be analysed to determine the composition of the calculi, as it is an essential element of the choice of treatment. 

Therapeutic approaches include the management of the stone itself and the treatment of the underlying mechanisms of the stone formation to prevent recurrences. Renal colic involving a stone smaller than 4 mm usually responds well to medical treatment, which consist of painkillers, anti-inflammatory agents and drugs dilating the ureter known as alpha-blockers, which allow the stone to be passed. 

Stones that are too large or have lead to complications require specific intervention, which vary according to the structure of the urinary tract and the location and size of the calculi. Handled by urologists, specialised treatments include extracorporeal shock wave lithotripsy (which fragments the calculi into tiny pieces that can be eliminated with urine), the removal of the stone with a device introduced through the ureter (ureteroscopy), or with various minimally invasive or classic surgical techniques. Surgery may also be indicated to correct a malformation of the kidney. Only calculi made of uric acid may be dissolved with medicines. 

The prevention of stone recurrence relies on medications and diet that are specific to the substance forming of the calculi. Intake of salt and animal protein should in any case be reduced. At risk individuals need to pass around 2 to 2.5 litres of urine per day. For those who have never suffered from stones, at least 1.5 to 2 litres of water are recommended and a minimum of 2 litres for those living in tropical countries to offset more intense sweating. Clear urine is a good sign that you are drinking enough water.

 

Dr Gerard Lalande is managing director of CEO-Health, which provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at [email protected].