Chronic Kidney Disease

How do you estimate GFR by age?

start with an average of 120 in young adults and subtract 1 for every year after 40

What is a normal GFR range for the elderly?

60-89

What kidney lab is not affected by muscle mass?

cystatin C (inaccurate with systemic inflammation)

What kidney lab is most beneficial in the acute setting?

Creatinine Clearance completed with a 24 hour urine collection

What are the risk factors for Chronic Kidney Disease (CKD)?

black, hispanic, native americans, increased age, diabetes, HTN, smoking, obesity, APOL1 Genetics (collapsing GN), NSAID use, lithium use, smoking

What are the physical exam findings of CKD?

abdominal bruits (renal stenosis), pericardial rub (uremic pericarditis), LV heave (LVH from chronic HTN)

What are the top causes of CKD?

Diabetes, HTN, Glomerulonephritis, Polycystic kidney disease, obstructive uropathy, recurrent AKI, autoimmune disease, drug-induced, vascular, and congenital

How is CKD classified?

Pre-Renal, Intrinsic, and Post-Renal (same framework/causes as AKI)

What is the leading cause of ERSD in the US?

Diabetes Mellitus (Type 1 & 2)

What is the triad for CKD caused by DM?

proteinuria, ↓GFR, & progressive HTN

What early markers are used for CKD caused by DM?

Microalbuminuria (UACR) and Retinopathy

What is the treatment for CKD caused by DM?

Glycemic + BP control

ACE / ARB

SGLT2

(P) Non-steroidal MRA (Kerendia / spironolactone)

* GASP *

How does hypertension cause CKD?

high pressure ➔ medial/intimal thickening ➔ chronic ischemia ➔ Arteriolar hyalinosis + interstitial fibrosis

What is seen on kidney ultrasound in CKD caused by Hypertension?

cortical thinning and atrophic kidneys

What are some associated comorbidities with secondary HTN that can progress to CKD?

Cortisol (Conn/Cushing Syndrome)

Renal Artery Stenosis & FMD

Sleep apnea

Metanephrines

TSH

What is the treatment for CKD caused by Hypertension?

antihypertensives, DASH diet, low salt, exercise, and stress reduction

What are causes of nephrotic glomerulonephritis by age?

- Children: Minimal Change Disease

- Young adults: FSGS

- Caucasian adults: Membranous

- Elderly: Amyloidosis & diabetic nephropathy

What are the complications of nephrotic glomerulonephritis?

Infection (losing immunoglobulins) and Thrombosis (losing antithrombin III)

What are the common causes of nephritic glomerulonephritis?

post-strep GN, IgA nephropathy, Lupus nephritis, ANCA vasculitis (PR3 and MPO)

What lab findings are consistent with nephritic glomerulonephritis?

RBC casts, dysmorphic RBCs, complements, anti-dsDNA, ASO, ANCA, positive biopsy

What is polycystic kidney disease?

inherited bilateral renal cysts (PKD1 > PKD2) associated with hepatic cysts, cerebral aneurysm, and MVP

What is a history finding that can prompt workup for polycystic kidney disease?

sudden death or brain bleeds

What is a physical manifestation of polycystic kidney disease?

Enlarged kidneys

What is the management for polycystic kidney disease?

Aggressive BP control (goal around 110 SBP) with ACE/ARB and Thiazide diuretics (Chlorthalidone) +/- tolvaptan. Lots of hydration!

How does obstructive uropathy or recurrent UTIs lead to CKD?

hydronephrosis infection that increases scar tissue and leads to dysfunction

What is a red flag frequency for UTIs?

>2 in 6 mo or >3 in 12 mo

What is the work up for obstructive uropathy/UTI related CKD?

1) CT / Ultrasound

2) UA, renal function panel

3) Bladder scan for post-void residual

What is the management for obstructive uropathy/UTI related CKD?

Cause-dependent with catheter, antibiotics, surgery, urology referral

What autoimmune diseases may progress to CKD?

Lupus nephritis, ANCA vasculitis, Anti-GBM, IgA nephropathy, Sjögren's, sarcoidosis, membranous

How does autoimmune disease progress to CKD?

Immune complexes / autoantibodies attack the glomerulus ➔ fibrosis

What is the workup for autoimmune related CKD?

1) UA for blood & protein

2) Targeted serologies (ANA, dsDNA, C3/C4, anti-GBM, IgA

3) Renal biopsy in ~99%

What is the management for autoimmune related CKD?

Immunosuppression (cyclophosphamide, rituximab, Tacrolimus), ACE/ARB for proteinuria, refer to rheumatology

What medications are associated with Pre-Renal Nephrotoxicity?

NSAIDs, ACE/ARBs, Diuretics, SGLT2, Calcineurin inhibitors, IV Contrast, Amphotericin B

What medications are associated with Intrinsic Nephrotoxicity?

ATN: aminoglycosides, cisplatin, contrast

AIN: PPIs, penicillins, NSAIDs

Crystal: acyclovir, methotrexate, indinavir

What medications are associated with Post-Renal Nephrotoxicity?

Anti-cholinergics (Urinary retention), Antihistamines, Opioids, Crystalluria

How does vascular disease / atherosclerosis lead to CKD?

stenosis or FMD ➔ Ischemic nephropathy ➔ fibrosis, tubular atrophy

What are some classic clues for vascular related CKD?

- Flash pulmonary edema

- Recurrent AKI after ACE/ARB start

- Asymmetric kidney size on imaging

What is the work-up for vascular related CKD?

- Renal artery duplex

- CT / MR angiography

- DMSA / MAG3 scan

What is the treatment for vascular related CKD?

- BP control, statins, antiplatelets

- Avoid volume depletion

- Stent if flash edema, AKI, severe HTN

What is the pathophysiology of Sickle Cell Nephropathy?

Microvascular occlusion + hypoxia + hemolysis ➔ papillary necrosis

What is a risk factor for Sickle Cell Nephropathy?

Risk higher in HbSS than HbSC

What are the classic symptoms for Sickle Cell Nephropathy?

polyuria, nocturia, hematuria

What is the workup for Sickle Cell Nephropathy?

- UA (protein / blood)

- UACR or 24-hr protein

What is the treatment for Sickle Cell Nephropathy?

- ACE / ARB

- Hydroxyurea

What is Vesicoureteral Reflux (VUR)?

Retrograde urine flow from bladder ➔ ureters / kidneys that is congential or from posterior urethral valves / neurogenic bladder

What is the pathophysiology of Vesicoureteral Reflux (VUR)?

Incompetent UVJ ➔ recurrent UTIs ➔ renal scarring ➔ CKD

What is the workup for Vesicoureteral Reflux (VUR)?

- Voiding cystourethrogram (VCUG)

- Renal US (hydronephrosis/scarring)

What is the treatment for Vesicoureteral Reflux (VUR)?

- Grade 1-2: often resolves — observe - Grade 3-4: antibiotics + surgery

What drugs can cause Chronic Interstitial Nephritis?

PPIs, NSAIDs, lithium, calcineurin inhibitors

What are etiologies of chronic interstitial nephritis?

toxins (lead), autoimmune, infections (TB, pyelonephritis), obstructive, hereditary, myeloma cast nephopathy

What is the workup for chronic interstitial nephritis?

- Sterile pyuria, WBC casts

- Hypokalemia, metabolic acidosis

- mild proteinuria (<300)

- Urine eosinophils

- Biopsy for fibrosis

What is the treatment of chronic interstitial nephritis?

Stop the offending agent / treat underlying cause

What causes waxy casts?

CKD (chronic)

What causes RBC casts?

Nephritic

What causes Muddy Brown casts?

ATN

What causes Eosinophils/WBC casts?

AIN / CIN

What causes Fatty casts (Maltese cross)?

Nephrotic

What is the minimum duration and GFR level for a CKD diagnosis?

GFR < 60 for > 3 months OR evidence of kidney damage (proteinuria, structural abnormality, biopsy findings)

What is the initial workup for a CKD diagnosis?

- BMP, CBC, UA with microscopy, UACR and UPCR

- Renal ultrasound (list line)

- BP logs, A1c, lipids

- Medication review

What may enlarged kidneys on US indicate?

diabetic nephropathy, amyloid, obstruction, PKD

What may small kidneys on US indicate?

renal artery stenosis, chronic CKD

What may be present on CT Renal?

Stones and masses

When is MRI/MRA Renal indicated?

Vasculitis evaluation and Renal artery stenosis assessment

What are the G categories of CKD staging by GFR level?

G1: ≥ 90 Normal

G2: 60-89 Mild (elder/muscle)

G3a: 45-59 Mild/mod

G3b: 30-44 Mod-severe

G4: 15-29 Severe

G5: < 15 Kidney failure

What is the presentation of CKD 1-2?

Asymptomatic - occasional nocturia, mild fatigue; proteinuria, hematuria, ↑BP, normal Cr/GFR

What is the presentation of CKD 3a/b?

Fatigue, nocturia, cramps, ↓ exercise tolerance; ↑Cr, mild ↑PTH, low Hgb, early acidosis

What is the presentation of CKD 4?

Anorexia, nausea, metallic taste, pruritus, RLS; anemia, ↑phos, ↓Ca, 2° hyperPTH, acidosis

What is the presentation of CKD 5?

Vomiting, confusion, asterixis, SOB, hiccups; uremic labs, ↑K, pericarditis, severe anemia

What should be used to track CKD?

eGFR, UACR, BP, electrolytes, acidosis, anemia +/- ultrasound

What is the monitoring frequency based on CKD?

G1-G2 ➔ yearly

G3a-G3b ➔ every 6 months

G4-G5 ➔ every 3 months

What does a decline > 5 mL/min/yr in GFR indicate?

progressive CKD

What does an acute drop in GFR indicate?

pre-renal, ATN, drugs

What does a fluctuating GFR indicate?

check volume, BP, protein intake

What are the indications for kidney biopsy?

Proteinuria > 3.5g/day, active urine sediment, rapid GFR decline, AKI with systemic symptoms, transplant dysfunction, glomerulonephritis

When may proteinuria be falsely elevated?

exercise, UTI/fever, orthostatic proteinuria

When is kidney biopsy contraindicated?

- small shrunken kidneys

- coagulopathy or high bleeding risk

- advanced CKD

- solitary kidney (relattive)

When is a nephrology referral indicated?

- GFR > 30

- Rapid progression (>5 mL/year)

- A3 albuminuria

- Resistant HTN, electrolyte issues

- unexplained anemia, hematuria, structural abnormality

- hereditary kidney disease

What are the most common complications of CKD related to GFR levels?

Anemia (40), Mineral/Bone disorder (50), uremic syndrome (20), metabolic acidosis (30), hyperkalemia (30)

How does CKD cause anemia?

↓ EPO production + ↑ hepcidin leading to functional iron deficiency

What is the workup for anemia of CKD?

- CBC, iron panel (TSAT, ferritin)

- B12 and folate

- check last colonoscopy / GI bleed

What is the treatment for anemia of CKD?

1) Oral or IV iron to replete stores (check for hemochromatosis hx)

2) B12 / Folate

3) EPO-stimulating agents when Hgb < 10

How does CKD cause metabolic acidosis?

↓ GFR ➔ impaired H⁺ excretion + ↓ bicarb production that drives bone resorption, muscle wasting, hyperkalemia, CKD progression

What is the workup for CKD metabolic acidosis?

BMP for CO₂ (bicarb) level

What is the treatment for CKD metabolic acidosis?

- Sodium bicarb ≥ 22

- Start 650 mg sodium bicarb BID

What is the chronic management of hyperkalemia related to CKD?

4.5–5.0: diet reduction, consider loop diuretic

5.0–5.5: Lokelma + bicarb (if <22) + loop diuretic

5.5–6.0: ↑ Lokelma + hunt hidden causes (NSAIDs, non-adherence, constipation)

> 6.0: send to the ER immediately

What are the 3 steps for the acute managment of hyperkalemia?

1. Stabilize: calcium gluconate

2. Shift: insulin/glucose, albuterol, bicarb

3. Eliminate: loop, Lokelma, dialysis

What labs are consistent with mineral and bone disorders caused by CKD?

- Low Ca

- High Phos

- Low Vit D

- High PTH (2° hyperPTH)

What is the treatment for mineral and bone disorders caused by CKD?

1) Phosphate control with diet and binders

2) Vitamin D repletion + analogs (calitriol, paracitol)

3) Cinacalcet or Parathyroidectomy (High PTH and High Ca)

What is the presentation of uremic syndrome?

accumulation of toxins leading to fatigue, anorexia, pruritus, cognitive change, RLS, hiccups, metallic taste

What is a characteristic physical exam sign of uremic syndrome?

Uremic pericarditis (rub / chest pain)

What labs are consistent with uremic syndrome?

BUN > 65, ↑Cr, acidosis, ↑K, anemia

When to start dialysis for chronic uremic syndrome?

uremic pericarditis, encephalopathy, refractory acidosis or hyperkalemia, volume overload unresponsive to diuretics, and progressive decline in nutrition/function

What GFR initiates renal replacement dialysis?

GFR < 10, or symptomatic uremia; discussion should begin when GFR is <20 / entering stage 4

What should be done for every patient with a fistula?

Always auscultate and palpate the fistula every visit. No thrill = possible clot

What is disequilibrium syndrome?

too rapid of a decrease in BUN and circulating fluid volume may result in cerebral edema and increased ICP

What are the preferred types of vascular access?

1) AV Fistula (last longing, lowest infection risk)

2) AV Graft (quicker, shorter lifespan)

3) Tunneled catheter (temporary, high infection risk)

What should be monitored monthly for hemodialysis?

K, Ca, Phos, PTH, Hgb, albumin

What are the complications of hemodialysis?

hypotension, cramps, infection, access thrombosis

Who are good candidates for Peritoneal Dialysis catheters?

younger patients, diabetics, small body habitus, motivated, stable home environment, awaiting transplant

What should be monitored monthly for peritoneal dialysis?

peritoneal fluid cell counts + adequacy testing