Kidney stones are an aggregation of crystalline structures amalgamated with proteins , that build up in the nephrons of the kidney.
Renal calculi means kidney stones and having a stone in any location of the urinary tract is called urolthiasis Third most common disorder of the renal tract ( after UTI and prostate problems ) The problem is increasing globally ( both developed and developing world ) and now it is thought that about 12 % of the world population will suffer with urolithiasis at some point of their life Geographic , racial and gender variations in its occurrence can be noticed Men seen to suffer more although this gap is narrowing Children are rarely affected with highest incidence rate seen in 40-60 age group In the US the lifetime risk of stone formation is reported to exceed 12 % for men and 6 % for women All ethnic groups are equally represented in the affected population Urolithiasis can now be deemed as a public health concern also called as a disease in evolution
What happens – Pathogenesis is poorly understood Etiology is possibly multifactorial Mechanism of stone formation ( calculogenesis ) is complex -interplay of several physiochemical processes described as - supersaturation - nucleation growth - aggregation - retention of urinary stone constituents within tubular cells Risk factors which are thought to play greatest role can be divided into 4 main categories (1 ) dietary (2 ) genetic (3 ) environmental (4 ) lifestyle Based on above the following risk factors can be found in literature
Family h/o urinary stones An abnormality of the urinary tract Obesity / Overweight with higher body fat percentages Hyperparathyroidism Metabolic syndrome Lack of physical activity Diet ( for e.g excessive animal protein consumption , high salt diet , extreme fasting ) Hypertension , diabetes and CKD Climate changes ( global warming ) , geographical conditions and seasonal fluctuations and the type of profession Water intake ( low fluid intake ) H/O bowel resection or inflammatory bowel disease ( incd enteric oxalate absorption due to malabsorption ) UTIs ( struvite stones ) Chronic diarrhoea & gout ( acidic urine )
Calcium stones- most common in most countries account for 75 % to 80 % of global stone prevalence specifically linked to obesity most Ca stones composed of calcium oxalate or calcium phosphate
Uric acid stones- accounts for about 3% to 10 % of all stone types supersaturated urea due to multitude of factors often 2ary to high purine diets most common cause is idiopathic
Struvite stones- also called infection stones & triple phosphate stones form in alkaline urine from infection with urea splitting microorganisms people with chronic urinary infections are prone to struvite stones
Cysteine stones- rare direct result of a genetic mutation that causes impairment in transport of an amino acid and cysteine cystinuria in urinary excretion
Drug induced – responsible for 1 % of all stone types drugs responsible include topiramate , Calcium + Vit D , steroids
Presentation- Symptoms would depend upon stone location if it is in the kidney , ureter or the urinary bladder may be asymptomatic in initial stages later signs can include - renal colic - flank pain - haematuria - obstructive uropathy - UTI - hydronephrosis.
History- History- taking would focus to cover if the patients has had a previous history of stones or any risk factors which contribute towards nephrolithiasis Previous problems for e.g UTIs , stones ( chance of recurrence following initial presentation is up to 30-40 % within 5 yrs ) , pyelonephritis Family history Any known anatomical defects for e.g solitary kidney , horseshoe kidney or h/o surgery Systemic co-morbidities for e.g diabetes , 1ary hyperparathyroidism , gout , inflammatory bowel disease , CKD, renal tubular acidosis , myeloproliferative disorders Drugs which can affect stone disease
Differentials – papillary necrosis with passage of a sloughed papilla renal emboli renal tumour UTIs pyelonephritis ovarian cyst torsion ectopic pregnancy GI conditions as obstruction , appendicitis , diverticulitis , cholecystitis , hepatitis & biliary colic herpes zoster
Renal colic- Renal colic may often be the 1st presentation – this happens when the stone moves from the renal pelvis into the ureter , causing ureteral spasm and possible obstruction.
Essentially obstruction of the ureter and several papers suggest that ureteric colic is a better term Spasm of the ureter around the stone is responsible for the pain which is accompanied by distension of the ureter , pelvicalyceal system and the renal capsule ( mediated by prostaglandin secretion ) Pain is generally of sudden onset and described by patients as the worse pain they ever had ( compared often to labor pain ) Pain may come in waves of various intensity ( colic ) and is accompanied by nausea and vomiting or patients may report a constant dull pain interrupted with exacerbations Classic location is in the costovertebral angle , lateral to the sacrospinous muscle and beneath the 12th rib- this may radiate to the flank , groin , testes or labia majora The patient is restless and unable to find a comfortable position ( pain from peritonitis conditions the patient would remain still ) – you may find the patient pacing around the examination table Patients may have painfree spells in between Haematuria may be noted.
Check vitals including temperature , examine the patient ( including testes in male patients ) , check urine ( dipstick ) and if possible consider NSAID by any route to relieve pain. There are no clear guidelines on management of suspected renal colic in primary care and given the wide differentials it may be difficult to ascertain who can be managed in primary care and who needs to be referred. A group of Durham GPs had addressed the issue in 2002 ( PJ Wright BMJ 2002 ) and their recommendations are still valuable – you may consider admission for the following group of patients .
age > 60 ( leaking abdominal aneurysm may present with similar symptoms ) persistent pain not relived by analgesia diagnostic uncertainty women of reproductive age and h/o delayed menstruation ( risk of ectopic pregnancy ) dehydration unable to take oral fluids/ medications due to nausea and / or vomiting symptoms of systemic illness , infection or anuria , fever > 37.5 CKD B/L obstructing stones are suspected personal preference h/o solitary or transplanted kidney.
Patients often require strong opiates ( e.g Morphine ) via para-medics , A&E to control the pain . The current NICE guidance on pain management recommends.
NSAID by any route IV paracetamol if NSAID contraindicated or are not providing adequate pain relief Consider opioids if both NSAIDs & IV paracetamol are contraindicated or are not providing adequate pain relief Do not offer antispasmodics to adults , children and young people with suspected renal colic.
Management – Management is complex and by specialist urology teams who will take into account - size , number , location and type of stone ( composition ) - presence of anatomical abnormalities or infection Associated complications ( like obstruction ) & / co-morbidities & suspected etiology National guidelines & local expertise in offering treatment The fact that up to 80 % of stones will pass spontaneously and increasing evidence now supports medical expulsive therapy ( MET )
NICE guidance – Offer urgent – ie within 24 hrs of presentation low dose non contrast CT to adults with suspected renal colic. for pregnant women within 24 hrs for children and young people with suspected renal colic. In children and young people if the US remains inconclusive. CT is the imaging of choice – it most accurately delineates ( high sensitivity and specificity ) stone size and location IVU is now historical and has been largely replaced by CT-KUB.
Medical expulsion therapy- Using an alpha-blocker like tamsulocin to facilitate spontaneous expulsion.
Shockwave lithotripsy ( ESWL ) Use of sound waves to fragment stones into small pieces which can be expelled easily- for smaller stones
Percutaneous nephrolithotomy-For complex , larger stones particularly those composed of cystine or struvite- allowing direct visualization and intracoprporeal lithotripsy.
Uretroscopic stone removal For stones in ureter & renal pelvis -particularly for pregnant , obese or coagulopathic patients
Open stone surgery -When other treatment fails + complexities.
Complications -Significant pain due to renal colic UTIs Urosepsis / abscess formation Urinary fistula Uretral scarring and stenosis CKD increased risk and ESRF CVD , diabetes and hypertension ( ^ ed risk ) Recurrence after initial episode ( high rate ) Treatment related complications.
+ ve family hx young age at onset nephrocalcinosis recurrent UTIs underlying conditions as renal tubular acidosis and hyperparathyroidism.
Preventative surgery – Increased water intake Primary dietary changes Pharmacological treatment ( for e.g potassium citrate or thiazide diuretic )
PATIENT INFORMATION LINKS
A comprehensive patient information page from the British Association of Urological Surgeons https://www.baus.org.uk/patients/conditions/6/kidney_stones/
Another useful page with plenty of diagrams from the Urology Care Foundation https://www.urologyhealth.org/urology-a-z/k/kidney-stones
National Kidney Foundation on kidney stones with useful videos https://www.kidney.org/atoz/content/kidneystones
Prevention of Kidney Stones – advice from North Bristol NHS Trust https://www.nbt.nhs.uk/sites/default/files/attachments/Advice%20for%20patients%27%20prevention%20of%20kidney%20stones_NBT002640.pdf
European Association of Urology has an excellent section on kidney and ureteral stones https://patients.uroweb.org/other-diseases/kidney-and-ureteral-stones/
Kidney Care UK on all matters related to kidneys – on kidney stones https://www.kidneycareuk.org/about-kidney-health/conditions/kidney-stones/
Treatment overview from NHS https://www.nhs.uk/conditions/kidney-stones/treatment/
A comprehensive guide to kidney stones and treatment from American Kidney Fund https://www.kidneyfund.org/kidney-disease/kidney-problems/kidney-stones/
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Kidney stone disease: an update on its management in primary care
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