Renal Colic (nephrolithiasis)

Question 1

Definition

Answer 1

Calcium oxalate stones form in collecting duct, deposited anywhere (renal pelvis to urethra)

Question 2

Epidemiology

Answer 2

Men
Elderly
hot, dry climate

Question 3

Risk factors

Answer 3

Chronic dehydration
High salt intake - excess sodium can form monosodium urate
Genetics = cysteine stones
Kidney diseases e.g. PKD
HyperPTH
UTIs
History of previous stone
Gout
Drugs = loop diuretic, antacids, acetazolamide, vit C+D

Question 4

Aetiology

Answer 4

MAIN CAUSES =
Calcium supplementation
Hyperparathyroidism
Cancer
- myeloma
- breast
- lung
Types of stones =
- Calcium oxalate stones -> hypercalcaemia, hypercalciuria
- Calcium Phosphate
- Uric acid stones = high purine intake, dehydration
- Struvite stone = produced by bacteria = UTIs
- Cysteine stone = autosomal recessive condition that causes decreased absorption of cystine = CYSTINURIA

Question 5

Pathophysiology

Answer 5

Excess solute in collecting duct = supersaturated = precipitates out of solution and crystallisation occurs as a NIDUS.
Stones cause regular outflow obstruction = HYDRONEPHROSIS
Obstruction causes prostaglandins release = natural diuresis = dilation + obstruction of renal pelvis (INCREASED DAMAGE + INFECTION RISK)

Question 6

3 most common obstruction sites

Answer 6

1. Pelvis-ureteric junction
2. Pelvic brim (ureters cross over iliac vessels)
3. Vesicoureteric junction (VUJ)

Question 7

Signs and symptoms

Answer 7

Pain – a classical colicky loin pain = LOIN TO GROIN PAIN = peristaltic waves
- The loin pain classically radiates down and round (L1-L2 nerve routes). It may go to the vulva/clitoris in females, and the tip of the penis in males
- Patient can’t lie still
Nausea / Vomiting
Haematuria
Sepsis
Fever
Dysuria (burning pain on micturition)
Tachycardia
Decreased blood pressure – can lead to septic shock

Question 8

Diagnosis

Answer 8

FIRST LINE = KUB X-ray (80%)
GOLD STANDARD = NCCT KUB (99%)
- Calcium oxalate = radio-opaque on x-ray
Bloods = FBC + U+E (suggests hydronephrosis)
Urinalysis = haematuria, pregnancy test

Question 9

Treatment

Answer 9

Symptomatic =
- hydrate + analgesia (e.g. diclofenac)
- Abx if UTI present e.g. gentamycin for pyelonephritis)
Stones normally pass spontaneously if small enough <5mm
Surgical if too big to pass = endoscopic sound wave lithotherapy = 6-10mm up to 20mm
or
percutaneous nephrolithotomy = keyhole removal of stones = large stones >20mm