10 High Yield Nephrology Pearls for Clinical Practice and the ABIM Board Exam (Part 2 of 2)

As discussed in part one, I have decided to take an article I recently tweeted out and summarize it here high yield nephrology pearls for clinical practice and ABIM Internal Medicine board exam preparation. The article was titled “The Top 10 Things Nephrologists Wish Every Primary Care Physician Knew” by Paige NM et al. The first 5 pearls were already discussed inpart one; in part two, I’ll discuss the final 5 pearls:

6. Anemia in Patients With CKD Should be Treated, but not Overtreated

• Anemia of Chronic Disease can lead to fatigue, left ventricular hypertrophy, and increased risk of cardiovascular events
• Hemoglobin target for CKD should be between 11 – 12 g/dL NOT to exceed 13g/dL
• Overcorrection of hemoglobin can result in higher risk of stroke, thrombosis, and hypertension
• Correct all other reversible causes of anemia

7. Phosphate-Containing Bowel Preps Should be Used With Caution

• Sodium phosphate bowel preparations are more convenient than some other preps (Easier to use)
• However, some studies have suggested that they can cause phosphate nephropathy leading to AKI or worsening CKD
• Instead use polyethylene glycol for the bowel prep (only downside is the volume that has to be consumed; Does not cause volume or electrolyte shifts)

8. Patients With Severe CKD Should Avoid Magnesium- or Aluminum-Containing Preparations

• These include over-the-counter agents such as Maalox and Mylanta
• Use of these agents can lead to hypermagnesemia, acute aluminum toxicity, worsening renal function, bone disease, and neurotoxicity
• The preferred quantitative test is spot urine protein to creatinine ratio (accurate & more convenient than 24-hr urine collection)
• A urine protein to creatinine ratio ≥ 1 has a higher risk of progression of CKD

9.Most Patients With Hypertension Should NOT Be Screened for Secondary Hypertension, But be Aware of Certain Clinical Clues

• In general 95% of patients have primary or essential hypertension, and only 5% have a secondary cause
• Clues include: Severe or difficult to control HTN, HTN that suddenly develops, or HTN that is associated with other clinical findings are some clues
• Hypokalemia: Consider primary hyperaldosteronism
• Headaches, palpitations, and sweats: Consider Pheochromocytoma
• Moon facies and/or striae: Consider Cushing Syndrome
• History of snoring in obese patient: Consider Obstructive Sleep Apnea
• Bruit on one side of the abdomen: Consider Renal Artery Stenosis
• Over-the-counter medications (NSAIDs, Birth Control Pills, or Decongestants)
• Non-compliance with Diet (High Sodium Intake)

10. Recurrent Nephrolithiasis, Needs a Metabolic Evaluation to Identify and Treat Modifiable Risk Factors

• Nephrolithiasis recurrence over a 10 year period for calcium oxalate stones is about 50% without treatment
• Family History of nephrolithiasis, inflammatory bowel disease, frequent urinary tract infections, or history of nephrocalcinosis should be referred to a nephrologist
• Initial workup should start with: diet history, medications, serum calcium, phosphorous, electrolytes and uric acid

Bonus: Cyclosporine and Tacrolimus (Calcineurin Inhibitors) Have Many Drug-Drug Interactions

• Any new medication or supplement that a post-kidney transplant patient requests should be reviewed first before prescribing
• St. John’s Wort, rifampin, phenytoin, and carbamazepine can all lower cyclosporine levels
• Diltiazem, verapamil, and erythromycin can increase cyclosporine levels
• Cyclosporine can interfere with certain statins such as simvastatin, increasing the risk of statin-induced rhabdomyolysis

Hopefully, between the two posts, you gained some high yield pearls for the management of your patients with chronic kidney disease. I’d also enjoy hearing from any nephrologists who read these posts, to get your comments and add any additional pearls of wisdom that general practitioners could use in their day-to-day practice as well as ABIM Internal Medicine exam certification/re-certification preparation.

References:

1. Markowitz GS et al. Acute Phosphate Nephropathy Following Oral Sodium Phosphate Bowel Purgative: An Underrecognized Cause of Chronic Renal Failure. J Am Soc Nephrol. 2005 Nov. 16 (11): 3389 – 3396. PMID: 16192415

2. Paige NM et al. The Top 10 Things Nephrologists Wish Every Primary Care Physician Knew. May Clin Proc. 2009 Feb; 84 (2): 180 – 186. PMID: 19181652

3. Phrommintidul A et al. Mortality and Target Haemoglobin Concentrations in Anaemic Patients With Chronic Kidney Disease Treated With Erythropoietin: A Meta-Analysis. Lancet 2007; 369 (9559): 381 – 388. PMID: 17276778