2. Anatomic and Physiology
• The kidneys are a pair of brownish-red structures located
retroperitoneal on the posterior wall of the abdomen from the T12 to
L3 in the adult.
• An adult kidney weighs 120 to 170g and is 12 cm long, 6cm wide, and
2.5cm thick.
• Well protected by the ribs, muscles, fascia, perirenal fat, and the renal
capsule, which surround each kidney.
• Kidneys consists of two distinct regions, the renal parenchyma and
the renal pelvis.
3. • The cortex contains the glomeruli, proximal and
distal tubules, collecting ducts and their adjacent
peritubular capillaries.
• Each kidney contains approximately 8 to 18
pyramids.
• The pyramids drain into renal calices that open
directly into the renal pelvis.
• The hilum, or pelvis, is the concave portion of the
kidney through which the renal artery enters and
the renal vein exits.
4. • Each kidney contains about 1 million nephrons, the
functional units of the kidney.
• The nephron consists of a glomerulus containing afferent
and efferent arterioles, Bowman's capsule, proximal
tubule, loop of Henle, distal tubule, and collecting ducts.
• The glomerulus is composed of three filtering layers: the
capillary endothelium, the basement membrane, and the
epithelium.
• Urine is formed in the nephrons in a three-step process:
filtration, reabsorption, and excretion.
• Water, electrolytes, and other substances, such as glucose
and creatinine, are filtered by the glomerulus
5. What are the functions of the kidneys?
• Urine formation
• Excretion of waste products
• Regulation of electrolytes
• Regulation of acid-base balance
• Control of water balance
• Control of blood pressure
• Regulation of red blood cell production
• Synthesis of vitamin D to active form
• Secretion of prostaglandins
6. Renal Failure
• Renal failure results when the kidneys cannot remove the body's
metabolic wastes or perform their regulatory functions.
• Renal impairment leads to a disruption in endocrine and metabolic
functions as well as fluid, electrolyte, and acid-base disturbances.
7. Epidemiology
Global burden (data From WHO)
• The GBD 2015 study estimated that, in 2015, 1.2 million people died
from kidney failure, an increase of 32% since 2005.
• In 2010, an estimated 2.3-7.1 million people with end-stage kidney
disease died without access to dialysis.
8. Acute kidney injury (AKI)
AKI refers to an abrupt decrease in kidney function, resulting in the
retention of urea and other nitrogenous waste products and in the
dysregulation of extracellular volume and electrolytes.
9. AKI stages – using KDIGO criteria
Stage 1 Increase in serum creatinine to 1.5 to 1.9 times
baseline, or increase in serum creatinine by ≥0.3 mg/dL (≥26.5
micromol/L), or reduction in urine output to <0.5 mL/kg/hour for 6
to 12 hours.
Stage 2 Increase in serum creatinine to 2.0 to 2.9 times
baseline, or reduction in urine output to <0.5 mL/kg/hour for ≥12
hours.
Stage 3 Increase in serum creatinine to 3.0 times baseline, or increase in
serum creatinine to ≥4.0 mg/dL (≥353.6 micromol/L), or reduction
in urine output to <0.3 mL/kg/hour for ≥24 hours, or anuria for ≥12
hours, or the initiation of kidney replacement therapy, or, in
patients <18 years, decrease in estimated glomerular filtration rate
(eGFR) to <35 mL/min/1.73 m2.
10. Epidemiology of AKI
• Global burden- 13.3 million cases every year. Annual incidence in
LMIC is 11.3 m cases.
• AKI has an incidence of 5–7% in hospitalized patients and 30% of
admissions to ICU and accounts for about 50-80% Mortality in ICU.
• Of 1.7 million deaths per year by AKI globally, an estimated 1.4 million
deaths are in LMIC.
11. What causes AKI?
• A condition that slows blood flow to your kidneys
• Direct damage to kidneys
• Urine drainage tubes (ureters) become blocked
12.
13. Who is at risk?
• Being hospitalized, especially serious condition whom requires intensive
care
• Advanced age
• Blockages in the blood vessels
• Diabetes
• High blood pressure
• Heart failure
• Kidney diseases
• Liver diseases
• Certain cancers and their treatments
14. Signs and symptoms of AKI
• Decreased urine output, (occasionally
urine output remains normal)
• Fluid retention, causing swelling in legs,
ankles or feet
• Shortness of breath
• Fatigue
• Confusion
• Nausea
• Weakness
• Irregular heartbeat
• Chest pain or pressure
• Seizures or coma in severe
cases
15. Diagnosis cont...
AKI is diagnosed as any of the following (KDIGO):
• Increase in SCr by X0.3 mg/dl (X26.5 lmol/l) within 48 hours; or
• Increase in SCr to X1.5 times baseline, which is known or presumed to have
occurred within the prior 7 days; or
• Urine volume of <0.5 ml/kg/h for 6 hours.
• Before diagnosing and classifying AKI, one should assess and optimize
volume status and exclude obstruction.
16. Management of AKI
Goals of management;
1. Determine its cause and recognizing prerenal causes or postrenal causes
2. Treating reversible causes, such as hypotension, volume depletion, or
urinary tract obstruction
3. Removing any active insults to minimize new injury
4. Identifying and treating the complications that may eventually require
RRT
17.
18. When to initiate RRT?
Complications of AKI that might require emergency RRT include the following:
• A-Acidosis
Severe metabolic acidosis (pH <7.1) and hypervolemia, unless acidosis can be
rapidly resolved by quickly correcting the underlying etiology (e.g, diabetic
ketoacidosis)
• E-Electrolyte imbalance
Hyperkalemia >6.5 mEq/L, hyperkalemia associated with symptoms or signs (i.e,
cardiac conduction abnormalities, muscle weakness), or hyperkalemia >5.5
mEq/L if there is ongoing tissue breakdown (e.g, rhabdomyolysis)
• I-Intoxication- Acute poisoning
• O- Overload- Pulmonary edema
• U- Uremic encephalopathy/Uremic pericarditis
Signs of uremia, such as pericarditis, or an otherwise unexplained decline in
mental status
19. Chronic Kidney Disease (CKD)
• KDIGO define CKD as either kidney damage or a decreased
glomerular filtration rate (GFR) of less than 60 mL/min/1.73 m2 for at
least 3 months.
20. How is CKD staged?
• Stage 1: Kidney damage with normal or increased GFR (>90 mL/min/1.73 m 2)
• Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m 2)
• Stage 3a: Moderate reduction in GFR (45-59 mL/min/1.73 m 2)
• Stage 3b: Moderate reduction in GFR (30-44 mL/min/1.73 m 2)
• Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m 2)
• Stage 5: Kidney failure (GFR < 15 mL/min/1.73 m 2 or dialysis)
21.
22. Signs and symptoms
• Patients with CKD stages 1-3 are generally asymptomatic.
• Signs of metabolic acidosis in CKD5: Protein-energy malnutrition, loss of
lean body mass, muscle weakness.
• Signs of water/electrolyte imbalance in CKD5: Peripheral/pulmonary
edema, hypertension.
• Anemia in CKD : Fatigue, reduced exercise capacity, impaired cognitive and
immune function, reduced quality of life, new onset of heart failure.
23. Diagnosis
The following markers of kidney damage may establish the diagnosis :
• Albuminuria (albumin excretion > 30 mg/24 hr or Alb:Cr ratio > 30
mg/g [> 3 mg/mmol])
• Electrolyte and other abnormalities due to tubular disorders
• Histologic abnormalities
• Structural abnormalities detected by imaging
• History of kidney transplantation
24. Other manifestations..
• Pericarditis: Can be complicated by cardiac tamponade
• Encephalopathy: Can progress to coma and death
• Restless leg syndrome
• Gastrointestinal symptoms: Anorexia, nausea, vomiting, diarrhea
• Skin manifestations: Dry skin, pruritus, ecchymosis
• Fatigue, increased somnolence
• Platelet dysfunction with tendency to bleed
25. Diagnosis
Laboratory studies:
• Complete blood count (CBC)
• Basic metabolic panel
• Urinalysis
• Serum albumin levels: Patients may have hypoalbuminemia due to
malnutrition, urinary protein loss, or chronic inflammation
• Lipid profile: Patients with CKD have an increased risk of cardiovascular
disease
26. Other tests:
Evidence of renal bone disease:
• Serum calcium and phosphate
• 25-hydroxyvitamin D
• Alkaline phosphatase
• Intact PTH levels
27. Imaging
• Renal USS: Useful to screen for hydronephrosis, tumor, or diffuse
adenopathy; small, echogenic kidneys are observed in advanced kidney
failure.
• Retrograde pyelography: Suspicion for obstruction
• CT scan: Define renal masses and cysts - most sensitive test for kidney
stones
• MRI: Patients who cannot receive contrast - Renal vein thrombosis
28. Biopsy
• Percutaneous kidney biopsy is generally indicated when kidney
impairment and/or proteinuria approaching the nephrotic range are
present and the diagnosis is unclear after appropriate workup.
29. Management
Goals of treatment;
1. Treatment of reversible causes of kidney dysfunction
2. Preventing or slowing the progression of kidney disease
3. Treatment of the complications of kidney dysfunction
4. Identification and adequate preparation of the patient in whom
kidney replacement therapy will be required
30. Treat complications:
• Anemia: Hb< 10 g/dL, treat with erythropoiesis-stimulating agents (ESAs),
after iron saturation and ferritin levels are at normal levels.
• Hyperphosphatemia: Treat with dietary phosphate binders and dietary
phosphate restriction
• Hypocalcemia: Treat with calcium supplements with or without calcitriol
• Hyperparathyroidism: Treat with calcitriol or vitamin D analogues or
calcimimetics
• Volume overload: Treat with loop diuretics or ultrafiltration
• Metabolic acidosis: Treat with oral alkali supplementation
• Uremic manifestations: Treat with long-term renal replacement therapy
(hemodialysis, peritoneal dialysis, or renal transplantation)
31. Indications for RRT
• Severe metabolic acidosis
• Hyperkalemia
• Uremic Pericarditis
• Uremic Encephalopathy
• Intractable volume overload
• Intractable gastrointestinal symptoms
• In asymptomatic patients, a GFR of 5-9 mL/min/1.73 m², irrespective
of the cause of the CKD or the presence or absence of other
comorbidities
32. Renal transplant
It is associated with better quality of life, lower medical costs, less
hospitalization, and improved survival compared with patients who
remain on dialysis.
33. References
• Medscape.com
• Online Medical Website (Uptodate)
• Davidson’s principles and practice of medicine 23rd Edition -
2018
• Tanzania Standard Treatment Guidelines (STG - 2021)
