It’s another sweltering summer day down South. Willie Nelson is trying to stay cool before his big show, doing what he does best–drinking iced tea. (You thought I was going to say something else, didn’t you?)  He begins to feel severe flank pain, writhing and sweating from the pain and summer heat.  No medicinal herbal remedy could stop this pain. You think, “Well, he’s done it again! Willie Nelson got stoned…”
Kidney-stoned!
Name 4 types of stones and their associated conditions
Calcium Oxalate: These make up 75% of all stones. They form with increased urinary excretion of calcium, such as in hyperparathyroidism, high calcium/meat diets, or in patients with Crohn’s/UC/IBD and increases in oxalate.
Struvite: These are the most common cause of staghorn calculi. They are caused by bacteria, specifically Proteus, Klebsiella, and Pseudomonas. Think chronic urinary infection with these.
Uric Acid: 10% of stones, most commonly in patients with gout. These are the ones that WILL NOT show up on x-ray.
Cysteine: 1% of stones; caused by in-born metabolic error. Â
Bonus question: which drug causes it's own stones?
Indinavir: Accounts for < 1% of stones and are made of the HIV protease inhibitor itself. But, only 4-10% of patients on this therapy will develop these stones. Â
What is the best test for diagnosis of urologic stones?
Non-contrast CT is both sensitive and specific for showing the stone as well as secondary signs like associated hydronephrosis and perinephric fat stranding.
Is there any role for KUB XR in stone diagnosis?
No. X-rays are neither sensitive (29-58%) nor specific (69-74%) and are not useful in diagnosis. Â
What is the role for ultrasound in diagnosis? What can it show and when can you rely on it for diagnosis?
Ultrasound can often pick up larger stones (> 5mm) in certain locations: proximal stones (renal pelvis) and distal stones. It is preferred for pregnant patients (no radiation) and good for those with prior diagnoses of stones to avoid continued radiation. Look for dense structures with shadowing and hydronephrosis.
Treatment for a stoner?
- NSAIDs are great because they help with both pain and ureter relaxation through prostaglandin inhibition.
- Metoclopramide may help with both renal colic and nausea
- Fluids? Not necessarily! Obviously replete patients if they are volume depleted, but loading them with fluids does not help force stone passage and may lead to distention of renal capsule.
- To alpha-block or not? Tamsulosin (or terazosin or doxazosin) MAY decrease pain and time to expulsion and are recommended for more proximal and larger stones. Encourage patients to take it at night before sleeping and also warn about orthostatic hypotension.
- Most patients can be discharged with GU follow-up.
When should you admit?
- Definitely admit for: Sepsis, renal failure, obstructed single or transplanted kidney
- Strongly consider admission for: Large stones > 6mm, significant comorbidities, obstruction with infection.
2nd bonus question: What real diagnoses has Willie had? Hint: they show true dedication to his loves of smoking and playing guitar...
Emphysema and carpel tunnel syndrome!
References
Manthey DE, Nicks BA. Chapter 97. Urologic Stone Disease. In: Tintinalli JE, Stapczynski J, Ma O, Cline DM, Cydulka RK, Meckler GD, T. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011.
Hippo EM
Special thanks to Drs. Willis and deSouza!
Remember, the boards and in-service exam are not always evidence-based. What we do in practice may not always be the right answer on your test. Frustrating, I know, but don’t let it stone you.
Kylie Birnbaum
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4 Comments
ablumenberg · July 1, 2016 at 7:48 pm
Great post Kylie!
Question:
What is your view on the role of opiates in managing renal colic pain?
jwillis · July 6, 2016 at 2:55 pm
I think opiates are a pretty well accepted pain management for colic. I usually start with NSAIDs and have good results without the opiate and use it as an adjunct for continued pain.
Some other interest adjuncts discussed that I have never used are beta agents, desmopressin and lidocaine.
iandesouza · July 6, 2016 at 6:13 pm
Renal colic is one of the few TRUE indications for ketorolac (over ibuprofen which has been shown to be equally effective for almost all other indications). I almost always manage these patients simply with IM ketorolac and a bedside sonogram (for hydronephrosis and more importantly to eval for AAA in older patients) +/- UA depending on my mood and how easy it is to get the patient to provide a sample for me. These should be easy “treat and release” patients with minimal labor involved.
Lurking Doc · July 7, 2016 at 11:50 pm
One question regarding an otherwise excellent (as usual) post:
Is there any evidence that a high calcium diet is associated with stone formation?