Question 31
A patient is scheduled for a renal biopsy. What are the risks that you would counsel them about?
At our institution, the following are the risk estimates:
- The incidence of gross hematuria is approximately 5-10%
- The incidence of significantly bleeding enough to delay discharge is approximately 1:100. This refers to persistent hematuria, or perinephric hematoma, which usually settles with conservative management
- A transfusion is occasionally necessary
- Serious bleeding complications sufficient to warrant interventions to stop bleeding are of the order of 1:1000
- Kidney biopsy can be life threatening in 1:5000-1:10000
Question 32
What are risk factors for developing contrast nephropathy?
Risk factors include:
- Volume depletion
- Preexisting renal insufficiency
- Diabetes
- Congestive heart failure (and other causes of decreased renal perfusion)
- multiple myeloma
- high volume of contrast
- high osmolality of contrast
Question 33
What is the clinical presentation of acute interstitial nephritis? List 5 drug classes that can cause this.
Acute interstitial nephritis classically presents with fever, maculopapular rash, eosinophilia, eosinophiluria, and urinary WBC casts. Eosinophiluria is neither sensitive (sensitivity 40%) nor entirely specific (specificity 72%, positive predictive value 38%).
The classic triad of rash, fever and eosinophilia is actually uncommon and only seen approximately 10% of the time. One can also see mild proteinuria (usually <1g/d) and other signs of tubular damage, such as renal tubular acidosis and Fanconi’s syndrome. Renal ultrasound generally reveals kidneys of normal to large size. Gallium scanning has been suggested as an aid to distinguishing this condition from acute tubular necrosis (ATN). It is negative in ATN but generally positive in interstitial nephritis.
Drug classes that can cause AIN:
- Penicillin analogs (methicillin,ampicillin, etc.)
- Cephalosporins
- Sulphonamides
- Other antibiotics such asrifampin and ciprofloxacin
- NSAIDS (including Cox-2 specificagents)
- Diuretics
- Proton pumpinhibitors
- Miscellaneous – includes a large number of drugs such as allopurinol and cimetidine.
If one is questioning whether a drug may be the cause of interstitial nephritis, it is generally best to consult a reference or perform a Pubmed/Medline search rather than memorize a list, especially given the large number of drug which have been implicated.
Question 34
What is the classification and definition of hypertension in pregnancy?
As per ACOG and ISSHP, the classification and definitions of hypertensive disorders of pregnancy are as follows:
- Preeclampsia/eclampsia: sBP >140 mmHg and dBP >90 mmHg and proteinuria >300 mg in 24 hours after 20 weeks of gestation
- Transient hypertension of pregnancy: Same as above but no proteinuria
- Chronic hypertension: Hypertension antedating pregnancy
- Chronic hypertension with superimposed preeclampsia: Worsening blood pressure with proteinuria >300 mg in 24 hours
References:
ACOG Committee on Obstetric Practice. ACOG practice bulletin. Diagnosis and management of preeclampsia and eclampsia. Obstet Gynecol. 2002;99(1): 159 67.
Brown MA et al. The classification and diagnosis of the hypertensive disorders of pregnancy: statement from the International Society for the Study of Hypertension in Pregnancy (ISSHP). Hypertens Pregnancy. 2001;20(1):IX-XIV.
Question 35
List 4 drugs safe to use for hypertension in pregnancy, and 4 reasons why ACE inhibitors are contraindicated.
It is safe to use the following drugs to treat hypertension inpregnancy:
- PO:
- methyldopa
- hydralazine
- labetalol
- nefidipine
- IV:
- hydralazine
- labetalol
- diazoxide
ACE inhibitors are contraindicated in all trimesters of pregnancy. If used, fetal anomalies include oligohydramnios, lung hypoplasia, craniofacial deformity and renal failure.
Reference:
Cooper WO, Hernandez-Diaz S, Arbogast PG, Dudley JA, Dyer S, Gideon PS, Hall K, Ray WA. Major Congenital Malformations after First-Trimester Exposure to ACE Inhibitors. N Engl J Med 354:2443, June 8, 2006
