Chronic Kidney Disease Overview

Chronic kidney disease (CKD) often progresses to end-stage renal disease (ESRD), requiring renal replacement therapy (RRT).
Patients with CKD frequently die from non-renal causes, particularly cardiovascular events.
Early diagnosis of CKD is crucial to delay progression and prevent cardiovascular complications.

Kidney Disease Improving Global Outcomes (KDIGO) defines CKD as abnormalities of kidney structure or function lasting longer than 3 months having implications for health.
National Kidney Foundation, Kidney Disease Outcomes Quality Initiative (KDOQI) provides another definition.
CKD is defined as kidney damage for more than 3 months (structural or functional abnormality) with or without reduced glomerular filtration rate (GFR), confirmed by urinalysis, imaging studies, or kidney biopsy.

Kidney damage or reduced kidney function lasting for over 3 months (documented).
A glomerular filtration rate (GFR) of less than 60 mL/minute/1.73 m2 with or without kidney damage.
Structural abnormalities in the kidney other than those related to a lowered GFR.

Reduction in nephron number, mediated by vasoactive hormones, cytokines, and growth factors.
Short-term adaptations of remaining viable nephrons (hyperfiltration, hypertrophy).
These responses eventually become maladaptive (distortion of glomerular architecture, sclerosis, nephron dropout).
Increased intrarenal activity of the renin-angiotensin axis, contributing to the initial adaptive hyperfiltration but leading to subsequent maladaptive hypertrophy and sclerosis.
Reduction in renal mass eventually leads to progressive decline in renal function over many years.

Glomerular filtration rate (GFR) is the best overall index of kidney function.
Decreases in GFR correlate with increasing symptoms and metabolic abnormalities.
A GFR below 60 mL/min/1.73 m2 is associated with a high risk of CKD complications like drug toxicity, metabolic endocrine complications, cardiovascular disease, and death.
Albuminuria (protienuria) is a marker of chronic kidney damage and also has prognostic value for the progression of CKD. It's also an independent risk factor for cardiovascular issues.

Advanced age, reduced kidney mass, low birth weight, racial/ethnic minority, family history, and low socioeconomic status.

Diabetes, hypertension, autoimmune diseases, polycystic kidney diseases, and drug toxicity.

Hyperglycemia (high blood sugar), elevated blood pressure, proteinuria (protein in the urine), and smoking.

History taking should consider: prenatal and postnatal information, hypertension details, diabetes mellitus, pre-eclampsia/pregnancy loss, family history, abnormal urea/creatinine, symptomatic urinalysis, and urine frequency/urgency/changes. Any relevant prior surgical history, medication history, infections, GI procedures using phosphate-containing enemas, nephrotoxic drug exposure or recent change in drug dose or new drug use, and history/presence of uremia symptoms should be collected.
Physical examination should evaluate: appearance (skin, edema, pallor, uremic odor), vital signs (blood pressure, pulse, saturation), funduscopy, cardiovascular system (apex beat, LV heave, pericardial rub), abdomen (distension, renal angle/mass, bruits), and Central Nervous System, particularly neurologic features.
Necessary investigations include: CBC, urinalysis (dipstick & microscopic exam), 24-hour urine protein, serum creatinine and urea, coagulation profile, electrolytes, calcium, phosphorous, Hb-related testing (hbsag, HCV, HIV, PTH, serum iron, and vitamins B12 and folate), ACR (albumin-to-creatinine ratio), GFR, renal ultrasound, and renal biopsy, if necessary.

GFR is classified, using ranges, to describe the severity of kidney damage (e.g. G1= normal or high, G2=mildly decreased, G3a=mild-moderately decreased, G3b=moderate-severely decreased, G4=severely decreased, G5=kidney failure).
Proteinuria (albumin excretion rate) is also graded to reflect severity (A1 = minimal, A2=moderate, A3=severe).

Differentiating AKI (acute kidney injury) from CKD through detailed history, previous sequential creatinine results and renal ultrasound. AKI can develop in patients with existing CKD.

Screening the general population for CKD isn't recommended but specific groups like those with hypertension, diabetes, cardiovascular conditions, hematuria/proteinuria on previous testing, known nephrotoxic drugs, structural renal disease, or a family history should be screened.

Albuminuria is recognized as a significant risk factor for cardiovascular disease, which is a leading cause of mortality/morbidity across all stages of CKD.
CKD-related ischemic vascular disease involves a combination of classical risk factors (e.g. hypertension, diabetes) and CKD-specific factors such as problems with hemodialysis (e.g. hypotension). Conditions include elevated cardiac troponin levels and possible complications in diagnostic testing.
Hypertension, often accompanied by left ventricular hypertrophy (LVH) frequently observed in advanced CKD and poor left ventricular function can also happen if hypertension isn't carefully managed. Low or very low blood pressure can have an equally poor prognosis compared to high blood pressure in patients with CKD.

Encouraging physical activity in line with cardiovascular health.
Smoking cessation and managing blood pressure/blood sugar to control CKD progression.
CKD stage-specific management includes vaccinations, blood glucose control, monitoring for electrolyte abnormalities (sodium, potassium), and kidney function monitoring and medication adjustments, when needed, as CKD progresses through stages and eventually prepare patients for dialysis if necessary.

Target HbA1c below 7% is important to delay complications in CKD patients with diabetes.
Gradual adjustments to insulin therapy are needed in CKD.

Dialytic therapy indications include: uremic symptoms, refractory hyperkalemia, persistent extracellular fluid expansion despite diuretics, metabolic acidosis, bleeding diathesis, and eGFR below 10 mL/min/1.73 m2.

Drug selection and dosage adjustments are necessary to prevent drug toxicity in CKD patients that frequently take multiple medications.
Adjusting for CKD stage, RRT status, and drug absorption is essential.