Kidney stones and calcium Flashcards
What are the 3 principle organs calcium is found
bone, gut, kidneys
What is the mechanism of PTH?
Increases blood calcium…
- acts on DCT to increase resorption
- increases osteoclast activity: breaks down bone `
After which surgery should you closely monitor calcium levels?
A thyroidectomy as by removing the thyroid you may accidentally remove the parathyroid gland
Which hormone increases the intestinal absorption of calcium?
Calcitriol/Vit D
Explain how Vitamin D goes from the sun/food to active calcitriol
- 7-dehydrocholesterol is in the skin and is converted into D3 cholecalciferol with UV, undergoes 2 hydroxylations:
D3 travels through circulation bound to transcalciferin, so only a small fraction is free
First hydroxylated to 25 hydroxyl Vit D in the liver
Kidney hydroxylates it into final calcitriol - D2 is from yeast and fungi and is converted in the liver and kidney into calcitriol
Where does calcitonin come from?
Parafollicular cells in the thyroid gland
What does calcitonin do?
Decreases blood calcium:
- Inhibits bone resorption by inhibiting osteoclasts
- Decreases kidney resorption
- Ensures calcium in the diet is being incorporated into bone
Define the following terms:
a) urolithiasis
b) nephrolithiasis
c) renal colic
a) urolithiasis: formation of stones anywhere in the upper urinary tract
b) nephrolithiasis: formation of stones in kidney
c) renal colic: the diagnosis of acute and severe pain due to a stone not being passed
Try to name 9 risk factors for developing a kidney stone
- Dehydration
- urine pH
- Age and gender
- FH: 2X increased risk
- Obesity
- Diet and Drugs: Vit D supplements, protease inhibitors, diuretics can increase calcium concentration in the urine
- Anatomical abnormalities; one kidney
- Certain diseases that cause hypercalcemia or affect absorption in the bowels, E.G; gout, Crohn’s, hypertension
- Renal failure
What are the 5 types of stones? What features are associated with each type?
- calcium salts (80%): low urine volume, raised urine pH, higher urinary concentrations of calcium, phosphate, oxalate, etc. and low concentration of natural inhibitors that might keep urine pH normal (e.g; citrate and magnesium)
- Uric acid: associated with hyperuricosuria - lots of uric acid in urine
- Struvite stones: magnesium, phosphate and ammonium from bacterial infections that hydrolyzed urea into ammonium - raises urinary pH
- Cystine stones: from cystinuria which is a genetic condition
- Other substances: e.g; xanthene
Describe the pain associated with renal colic
Radiates up the loins and flanks, and fluctuates in intensity
List 4 other possible symptoms of kidney stones other than pain
- restlessness
- vomiting
- hematuria: due to damage to the epithelia
- Obstruction can cause infections; leading to fever, sweats, dysuria, etc.
List the 3 main locations where a kidney stone can get stuck
- Ureteropelvic junction: leaving kidney
- Mid ureter/pelvic inlet
- Ureterovesical junction: entrance to bladder
What is the differential diagnosis for kidney stones?
- Ruptured AAA
- If loin pain on R side: appendicitis
- If pain on L side: diverticulitis: inflamed pouches in lining of the intestine, common in elderly
What 2 investigations might you do in someone presenting with symptoms alike to a kidney stone?
- Urinalysis: looking for hematuria, nitrites and leukocytes can indicate an infection
- Blood test: see if there is urea, creatinine and electrolytes
FBC
CRP: c reactive protein indicates inflammation
Blood cultures
When would you admit a patient for kidney stones? (5 things)
- systemic infections/shock/fever
- AKI
- pregnancy
- dehydrated and can’t take oral fluids (e.g; vomiting)
- not responding or worsening pain after an hour of treatment
What is the golden standard for imaging a kidney stone?
CT KUB
What should you equip a patient with kidney stones with when sending them home?
- Non-steroidal anti-inflammatory drugs, e.g; NSAIDs
- Antiemetic can be effective against vomiting and nausea
- Explain to them to pee into a sieve as they might pass the stone themselves, and in that cause the stone can be kept and analysed
- Follow up appointment in 7 days
If there is no access to a CT KUB, what other tools can you use for imaging?
MRI, Ultrasound, X ray, ureteroscopy
Which stone commonly leads to hydronephrosis and why? What can you do if this develops?
Struvite stones as they have a tendency to stick together, a nephrostomy can be done where a tube is inserted into the back which will drain the urine until the stone can be removed
What can you insert after a procedure has been done to remove kidney stones to stabilize the ureters? How long does it stay for?
A ureteric stent; 4-14 days
What drugs may help facilitate a spontaneous passage of stones? What are the criteria for giving these?
Alpha-blockers, Ca2+ channel blockers: the patient has to be recently diagnosed, no systemic infection, adequate renal function and a stone <10 mm
What is extracorporeal shock wave lithotripsy?
Non-invasive outpatient treatment that focuses shock waves to break up the stone until particles are small enough to be passed
What does Ureteroscopy do?
Camera with use of laser to remove stone
What is the most surgical option there is to remove a kidney stone?
Percutaneous nephrolithotomy: pass a scope through back of kidney to break up the stone which can be extracted through the nephroscope or removed
What is the prognosis for a recurrence and a spontaneous passage?
50% will have one more kidney stone and 10% will have multiple more
If the stone is >6mm there is a low chance, and if it is higher up in the ureter. If it is more distal and small, there is a higher chance of it being passed spontaneously
What are some complications of having a kidney stone
- Complete obstruction of urinary flow: reduced GFR, AKI, infection
- Ureteric stricture, can damage endothelial layer and bacteria can get into bloodstream = sepsis
What can you do to prevent a kidney stone from reoccurring?
- iIncrease fluid intake
- balanced diet; e.g; reduced salt
- maintain a healthy weight
- to avoid calcium stones: avoid eating oxalate-rich foods; e.g; strawberries and rhubarb
- Uric acid stones should avoid excessive dietary intakes of urate rich foods like fish
