1. Renal Stone Disease
2013
Mini-Lecture

2. Objectives Identify common risk factors for renal stone disease
Identify common signs and symptoms for renal stone disease
Know the common types of renal stones
Familiarize with basics of renal stone management, including knowing when to consult urology

3. Case
49 year old woman with history of hypertension, diabetes presents with four day history of right sided flank pain and “pink urine.” What is the most appropriate imaging to diagnose this patient with renal stone disease?
A: KUB
B: Ultrasound
C: Contrast-enhanced CT
D: Non-Contrast CT
The answer is D. The rationale will be explained toward the end of the lecture

4. Etiology Supersaturation of urine with solutes
Solubility is affected by urine pH, volume and total excretion
Those factors can often be modified with medications and diet
On the last point, emphasize that the vast majority of first incidence of renal stones can be prevented by dietary changes, while the vast majority of recurrence can be prevented with dietary changes with appropriate medications.

5. Risk Factors Male sex Obesity Family History
H/o stone disease (1/2 will have recurrence)
Dietary factors
Lower fluid intake, higher animal protein, higher Vitamin C
Medical factors
Pre-disposing medical factors, such as hyperparathyroidism, are a complex list, and will not be addressed here

6. Signs/Symptoms Typical symptoms Sudden onset
Unilateral colicky flank pain radiating to groin (localization of pain evolves as stone migrates)
Often with nausea/vomiting
Hematuria (microscopic or gross)
In the case of renal stone disease, typical symptoms are very typical. Of these, hematuria has very high sensitivity.

7. Differential Differential for flank pain with hematuria UTI
Renal Cell Carcinoma
Ectopic pregnancy
Dissecting AAA with renal artery involvement
Explanation for the bullet points
Renal Cell carcinoma: The bleeding can cause clots that lodge in ureter to produce colic
Ectopic pregnancy: vaginal bleeding mistaken for hematuria

8. Types of Stones In order of prevalence Calcium Oxalate
Calcium Phosphate
Struvite
Urice Acid
Cystine

9. Workup Urinalysis: may show
Hematuria (90% sensitive)
Signs of infection
Crystals
Elevated pH (urea-splitting bugs?) or low pH (RTA?)
Metabolic workup: Consider only if recurrent
Urinalysis plays a significant role in narrowing the differential to renal stones.
Metabolic workup that often requires 24 hour urine collection, should only be considered the patient has an established diagnosis of recurrent renal stones, and should only be pursued after the acute phase of the episode has passed. This is because during the acute phase, patients are often over/under hydrated, are on unusual (for the patient) medications or diet.
The metabolic workup can consist of:
Ruling out hyperparathyroidism, distal RTA, hyperoxaluria, excessive vitamin D, gout, chronic diarrhea, osteoporosis.

10. Workup
Imaging
Non-Contrast helical CT with Stone protocol is the gold std (can detect stones not visible by KUB/IVP and has significantly better sensitivity/specificity)
Ultrasound: For patients needing avoidance of radiation (pregnant, childbearing age)
IVP: No longer favored due to lower sensitivity, HIGHER radiation exposure
KUB: Will miss radiolucent uric acid stones, small stones, stones with overlying bony structures.
In the vast majority of cases, Non-contrast CT should be used to establish the diagnosis.
Emphasize that contrast is NOT recommended.
Also, Ureteral dilation withOUT a stone present on imaging may represent the recent passage of one.

11. Treatment Urologic Intervention? So when to consult urology?
X<5mm : most pass spontaneously. Possible observation and pain control
X>5mm : less than 20% chance of passage and may need urologic intervention
So when to consult urology?
If > 5mm
For ANY size with ….
Urosepsis, AKI, anuria, unyielding N/V/Pain -> Inpatient consult
Failed conservative management and stone did not pass spontaneously -> Inpatient or Outpatient consult depending on severity
Algorhythm on the following page

13. Summary Identified common risk factors for renal stone disease
Identified common signs and symptoms for renal stone disease
Know the common types of renal stones
Familiarized with basics of renal stone management, including knowing when to consult urology