Background
DM is the #1 cause of CKD in the U.S. HTN is #2.
GFR decreases with age. On average, GFR decreases by 10 per decade starting from age 20.
Definition of CKD.
Staging of CKD.
Diagnosis
H&P:
Screen all patients with Risk Factors for CKD.
DDx and Etiology:
Screening studies for CKD
-eGFR (estimated from Creatinine and other parameters like gender, age, and race)
-Protein to creatinine ratio or albumin to creatinine ratio (from a random or spot urine sample)
-UA with microscopy (to examine urine sediment/casts/cells etc)
-Blood pressure
Diagnostic studies for CKD
-CBC, CHEM 7: Na, K, Cl, CO2, BUN, Cr, Glucose. Get STAT EKG if the patient is Hyperkalemic.
–UA with microscopy (look for casts, RBC, WBC, protein); Urine Culture (if infection suspected)
-Urine protein to creatinine ratio or albumin to creatinine ratio
-Confirm the diagnosis by repeating abnormal lab. E.g. repeat CMP and spot urine protein/creatinine ratio.
-Renal ultrasound (to evaluate for potentially reversible causes).
-Optional studies: KUB (for stones), CT Abdomen (for masses if suspicion exists from H&P)
-Consider labs to rule out GN and vasculitis.
Treatment
CKD Clinical Action Plan.
Goal: to slow progression.
-Diabetes control (goal HbA1c <7)
-Blood pressure control,
-ACE-I/ARB (reduction of proteinuria)
Monitor for complications of CKD.
Refer to nephrology as appropriate.
Important CKD links and pearls
- “Patients with stage 3a to 5 CKD should have serum calcium, phosphorus, 25-hydroxyvitamin D, parathyroid hormone, and alkaline phosphatase levels checked regularly; abnormal levels may indicate the presence of renal mineral and bone disorders.” AAFP 2017
- DEXA scan (densitometry) can be used in patients with stage 1 to 3a CKD to screen for osteoporosis in the same way as for everyone else. However, DEXA scan is less accurate, and not recommended, for people with a more CKD. If you really need to to know the bone health of someone with more advanced CKD, you need a bone biopsy. Ouch! (AAFP 2017)
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Interventions that are proven to slow the progression of chronic kidney disease are controlling DM, HTN, and adding ACE-I/ARB.
“Elevated microalbuminuria should have this finding confirmed on at least one of two additional spot tests, since temporary factors other than nephropathy can also result in microalbuminuria. Once a diagnosis of chronic kidney disease is confirmed, renal ultrasonography should be ordered to detect potentially reversible causes.
A 24-hour urine is not necessary since the urine microalbumin/creatinine ratio correlates well with a 24-hour urine for albumin. ” ABFM
“Risk factors for renovascular disease include hyperlipidemia, cigarette smoking, age >50 years, coronary artery disease, peripheral arterial disease in other vascular beds.”
“Offer to test for CKD using eGFR, creatinine, and ACR to people with any of the following risk factors:
diabetes
hypertension
acute kidney injury
cardiovascular disease (ischaemic heart disease, chronic heart failure, peripheral vascular disease or cerebral vascular disease)
structural renal tract disease, recurrent renal calculi or prostatic hypertrophy
multisystem diseases with potential kidney involvement – for example, systemic lupus erythematosus · family history of end-stage kidney disease (GFR category G5) or hereditary kidney disease
opportunistic detection of haematuria.
Monitor eGFR at least annually in people prescribed drugs known to be nephrotoxic.” NICE.org.uk
Further Reading / References.
Algorithm: https://www.nice.org.uk/guidance/cg182/resources/algorithms-pdf-498987181
https://www.aafp.org/afp/2017/1215/p776.html
http://www.aafp.org/afp/2012/1015/p749.html