CMPP: Kidney Stones

typical flank pain

--> acute ureteral distension

when one has a kidney stone, stimulation of the renal pelvis and calyces secondary to an interureteral stone results in...

ilioinguinal, genitofemoral

in the lower ureter, pain signals are distributed through the _________ and __________ nerves resulting in classic pain radiation patterns

N/V

common innervation pathway of the renal pelvis and GI tract results in what symptoms in 50% of pts?

supersaturation

the key process in the development of kidney stones is...

calcium oxalation, uric acid, and cysteine

what are some examples of stone promoters (substances in the urine that predisposes to stone formation)

low

--> low fluid intake results in low urine volume leading to high concentrations of stone-forming solutes in the urine

stone promoters can form crystals if urine output is...

by preventing crystals from sticking t renal tubules

how do stone inhibitors protect against stone formation

citrate, magnesium, pyrophosphate

what are some examples of stone inhibitors (protect against stone formation)

hypercalciuria

what is the most common metabolic abnormalitiy associated with stone-formation?

increased protein diets, increased Na diet --> increased urinary calcium

what are some other risk factors for stone formation?

low urine volume, increased promoters, decreased inhibitors

what are the three MAIN predisposing factors to stone formation?

yes -- radiopaque

can you see calcium-based stones on plain films?

calyceal, painless

stones develop within the ______ system, and they are generally _________ within the calyces/renal pelvis

when they become intraureteral

when do stones begin to cause pain?

the stone is NOT the cause of their pain

what does it mean if a pt is having pain and the CAT scan reveals an infrarenal stone?

calcium --> calcium oxalate is most common

the vast majority of stones are _______ based

struvite stones, uric acid stones, and cystine stones

less common types of kidney stones

idiopathic hypercalciuria

hyperparathyroidism (less common)

what are some causes of calcium-based stones?

acidic, alkaline

calcium oxalate stones form in ______ urine, while calcium phosphate stones form in _______ urine.

magnesium, ammonium, and phosphate

struvite stones contain...

suffering recurrent UTIs secondary to urea splitting organisms

--> Proteus and Klebsiella

--> pts with abnormal urinary tract anatomy and patient's requiring frequent bladder catheterizations are also at risk

there is an increased risk of forming struvite stones in patients...

women (due to higher propensity for UTIs)

what gender is at higher risk of struvite stones?

painless, radiopaque

Struvite stones may be _____, and are _________ on KUB.

Staghorn formation

struvite stone that extends to full the renal pelvis

hyperuricosuric states (gout and myeloproliferative disorders)

uric acid stones may develop as part of...

acidic, purine (organ meats)

uric acid stones are formed in _______ urine, and are also caused by diets high in _____.

no! but can be seen on CT

can uric acid stones be seen in XR?

cystinuria (autosomal recessive), hexagonal crystals, acidic

cystine stones are associated with __________, appear as ___________, and form in _______ urine.

HYDRATION

Citrate -- chelates Ca forming highly soluble complexes

Magnesium supplementation

Fiber-rich diet

what are some primary protective factors against kidney stones?

sudden, severe pain which may wax and wane (renal colic)

N/V, hematiroa, dysuria, urinary frequency

clinical features of kidney stones (quality of pain/associated symptoms)

there is bilateral obstruction, a single functioning kidney, or significant preexisting CKD

anuria/azotemia secondary to post-renal AKI only occurs when....

pain localized to the flank and upper abdomen

if a stone is upper ureteral, where will the patient be having pain?

mid and lower abdominal pain

if a stone is mid-ureteral, where will the patient be having pain?

pain radiates to lower pelvis, groin, testicle, or labia

--> may have associated with urinary frequency/urgency

if a stone is lower ureteral/at the ureterovesical junction, where will the patient be having pain?

sudden, intense unilateral flank pain

pain may radiate based on location of the stone

restlessness (vs peritoneal causes which cause you to lie still), N/V, irritative urinary symptoms

--> NOT usually associated with fever, chills, or diarrhea

what is usually present on the HPI for one with a kidney stone?

Cancer (paraneoplastic syndrome/tumor lysis syndrome)

Hyperparathyroidism

Sarcoidosis

Gout, multiple myeloma, chemo

IBD

Recurrent UTIs

PMH that could point you towards a kidney stone

AAA

if a pt presents with abdominal pain, is >60 and they have no history of kidney stones, what is this a red flag for?

+ FH

adolescents following rapid wright gain

genetic factors in children

dietary factors

Misc historical factors associated with kidney stones

significant distress secondary to pain, pacing, restless, intensely diaphoretic, writhing in pain

general appearance of one with a kidney stone

tachycardia, HTN, CVA tenderness, abdominal distension (ileus), NO significant abdominal tenderness

PE findings for one with a kidney stone

kidneys are retroperitoneal

why is there usually no significant abdominal tenderness associated with kidney stones

AAA!!

can also include cholecystitis, pancreatitis, gastritis, musculoskeletal/mechanical back apin

--> many of these are associated with significant abdominal pain and tenderness, which is NOT a symptom seen with kidney stones

Ddx for one with upper abdominal pain (what else can it be other than upper-ureteral stones?)

Appendicitis/diverticulitis

--> many of these are associated with significant abdominal pain and tenderness, which is NOT a symptom seen with kidney stones

Ddx for one with lower abdominal pain (what else can it be other than mid-ureteral stones?)

ruptured ectopic, ovarian torsion, tubo-ovarian abscess, PID,ruptured ovarian cyst, testicular torsion, epididymitis, UTI

--> many of these are associated with significant abdominal pain and tenderness, which is NOT a symptom seen with kidney stones

Ddx for one with pain in the labia, testicles, suprapubic region, or irritative voiding symptoms (what else can it be other than ditsal ureteral stones?)

significant abdominal pain/tenderness -- not associated with kidney stones

what is a PE result that can help to differentiate kidney stones from other conditions (e.g ectopic pregnancy rupture, testicular torsion, diverticulitis)

no

does back pain and hematuria always equate to a kidney stone?

T12-L3, lateral aspect of the TPs

kidneys are typically at vertebral level _______, and the ureters travel along the _______________.

a radiopaque calcium-based/struvite stone

--> difficult to differentiate from other densities

--> does not allow for identification of ureteral obstruction

KUB (plain XR) may reveal...

follow-up after a stone is diagnosed on a CT

KUB is primarily used as...

Noncontrast Low-dose radiation Spiral CT scanning

--> detects TINY stones

--> assesses degreee of hydroureteronephrosis

--> recommended for diagnosis in first-time episodes, unclear dx, or prox infection suspected

what is the study of choice for one with kidney stones?

less radiation and easier to perform on these populations than a CT

--> can identify hydronephosis and small/radiolucent stones

why is ultrasonography the imaging modality to choice in children/pregnant patients

Intravenous pyelography

before the widespread use of CT, what WAS the study of choice for kidney stones?

Intravenous pyelography

contrast is injected into a peripheral vein; plain XRs are taken at intervals as the dye travels through the urinary tract; gives info regarding renal function

does not reveal alternate pathology

contraindicated with underlying CKD

what are some issues with IVP?

Hematological disorders/Hyperplasia (BPH)

Infections (UTI)

Trauma

Tumor of the urinary tract

Exercise

Renal (Glomerulonephritis)

Stones

Ddx for hematuria (HITTERS)

Pyonephrosis

infection PROXIMAL to an obstructing stone; urologic emergency

presence of UTI and a stone

what signs/symptoms raise concerns for pyonephrosis

recurrent stones, initial presentation at age < 30 years, severe AKI

indications for 24-hour urine studies with kidney stones

decreased urinary volume

hyprercalciuria

hyperoxaliruia

hyperuricosuria

hypocitraturia

what are some common abnormalities found with 24-hour urine studies

IV fluids to correct dehydration (0.9 NS)

IV NSAID (ketorolac)

--> don't give if pt has CKD

IV antiemetic (Zofran)

*management comes BEFORE evaluation

acute management of kidney stones

excess hydration could worsen pain -- adequate hydration is now what's indicated

why is aggressive hydration no longer indicated in the acute management of kidney stones?

IV NSAID: blocks prostaglandin formation --> relaxes the ureteral smooth muscle

Ketorolac (Toradol) MOA

pregnancy and CKD

--> if Toradol constricts afferent arteriole, can further decrease GFR and then worsen kidney disease

Ketorolac (Toradol) contraindications

Morphine sulfate

what is the opiate drug of choice for kidney stones?

binds to CNS opioid receptors

Morphine sulfate MOA

N/V, respiratory depression, altered mental status, hypotension

Morphine sulfate side effects

NSAIDS -- due to effect on relaxing ureteral smooth muscle, lower side effect incidence, minimal risk of addiction, no effect on ability to drive, less likely to require repeat doses

what drug for pain control is more effective in the tx of kidney stone pain?

intractable pain

intractable vomiting

AKI

urosepsis

anuria

stone size

admission criteria for kidney stones

unremitting pain

high-grade obstruction associated with increasing creatinine

bilateral obstruction or obstruction with a solitary kidney

obstruction + urosepsis (pyonephrosis)

indications for surgery with kidney stones

Ureteral stent placement

long, hollow tube passed cystoscopically through the urethra and bladder into the affected ureter; tube occupies the entire length of the ureter from the kidney to the bladder; forms coil at renal pelvis and bladder ends; ensures urine passage; should NOT be left in place for more than 3 mo

guarantees drainage of urine from the kidney

gently dilates ureter - significant pain relief

how does ureteral stent placement help to treat kidney stones?

discomfort secondary to bladder irritation/spasm

risk of blockage, dislodgment, or infection

side effects/complications of ureteral stents

drains collection of pus

why is a ureteral stent one of the primary tx options for pyonephrosis

Cystoscopic stone retrieval

Extracorporeal shock wave lithotripsy

Percutaneous nephrolithotomy

Open nephrolithotomy/pyelolithotomy

tx for kidney stones in which an incision is made through the flank into the renal cortex (nephrolithotomy) or renal pelvis (pyelolithotomy) to remove a stone lodged in the renal pelvis

anatomic difficulties precluding other interventions and the presence of complex (struvite) stones

indications for Open nephrolithotomy/pyelolithotomy

Hydration to maintain adequate urine output

Analgesia (opiates/NSAIDs) + anti-emetics

Alpha-1 antagonists

outpatient management of kidney stones

Intractable pain, vomiting, fever, chills, decreased urine output

red flags in pt education for one with kidney stones

analgesic of choice for outpatient management of kidney stones

Oxycodone/acetaminophen (Percocet)

what opiate is considered first line for outpatient management of pain associated with kidney stones?

Hydrocodone/acetaminophen (Vicodin)

--> less potent than oxycodone

other opiate options for outpaitient management of kidney stations

Ondansetron (Zofran) -- ODT (on da tongue)

what is the anti-emetic of choice for outpatient management of kidney stones

Tamsulosin (Flomax)

what is the alpha-1-antagonist of choice for the outpatient management of kidney stones

relaxes ureteral smooth muscle facilitating stone passage -- increases the likelihood of spontaneous passage, decreases the time for stone passage

Tamsulosin (Flomax) MOA

orthostatic hypotension and syncope

Tamsulosin (Flomax) side effects

less of a chance of dealing with major hypotensive symptoms -- since the pt will be asleep

why is Tamsulosin (Flomax) given at bedtime?

have the patient sit when they pee

how can we prevent micturition syncope with Tamsulosin (Flomax)

< 5 mm

stones of what size tend to pass spontaneously?

> 10 mm

stones of what size DO NOT tend to pass spontaneously?

stone is likely to pass spontaneously/can be managed outpatient

patient must maintain good hydration

strain urine (first time) so stone can be abalyzed

analgesics, antiemetic, alpha-blocker

follow weekly to monitor progress

should pass within 4 wks -- surgery if not

patient education for "small" kidney stones

less likely to pass spontaneously -- early surgical intervention

urologist

lithotripsy/cystoscopy with basket extraction

patient education for "bigger" kidney stones

often require hospitalization

emergent stent or percutaneous nephrolithotomy if renal function is jeopardized or a secondary infection has developed

< 2 cm --> lithotripsy

patient education for "biggest" kidney stones

normal calcium diet

avoid oxalate-rich foods

avoid high protein diet

Thiazide diuretics

Hypocitraturia -- potassium citrate

Hypomagnesiura -- magnesium supplements

long-term therapies for calcium-based stones

Allopurinol -- prevents uric acid production

avoid purine-rich foods (alcohol/organ meats)

Potassium citrate (alkalinizing agents) to prevent acidic urine formation

long term therapies for uric acid stones

Potassium citrate -- DRUG OF CHOICE

--> metabolized to potassium BICARBONATE

oral alkalinizing agents

calcium oxalate, uric acid, and cystine stones

oral alkalinizing agents are the tx of choice for...

UTIs

urine alkalization may increase the risk of...

usually surgical removal -- but can get lithotripsy

antibiotic coverage may be necessary (urea-splitting bacteria)

anatomic abnormalities should be corrected

tx for stuvite stones