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Renal Disorders
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- 1Normal Kidney function: Anatomy factsretroperitoneal (behind peritoneal cavity)
Kidneys dont lie symmetrically (left slightly higher & vein longer)
For this reason that left is transplant kidney - 25 major functions of kidneys1. removal of water & waste from blood
2. maintain electrolyte balance
3. maintain acid-base balance
4. regulate BP by renin secretion (endocrine role)
5. stimulate production of RBC by erythropoietin secretion (endocrine role)
ALSO others e.g. convert Vit D into active form - 3The Nephron: what is it and how many are thereFunctional unit of the kidney!
~1million in a healthy kidney - 4How much of cardiac output do kidneys receive?1/4 (~1300 mls/min - so around 1600 to 1800 L/day)
- 5What is GFR (Overview)Glomerular filtration rate (normal >120 mls/min) 'rate at which blood is cleared of waste product
- 6the math of GFRkidneys filtering waste products at a rate of 120 mils/min 24 hours a day = 120 x 60 x 24 = 170L of ultrafiltrate produced by kidneys and will ultimately be reduced to the 1.5 – 2 L of urine that we normally excrete each day
- 7The role of glomerulusto produce ultrafiltrate
- 8The role of NephronTo modify content & reduce volume
- 9Why do we need ~1M nephrons?-about 60 to 80% of the water and sodium, chloride is reabsorbed in the proximal convoluted tubule along with all the potassium, bicarbonate, glucose and amino acids, more water is absorbed in the descending loop of Henley shown here and then, more sodium and chloride in the ascending loop
-further sodium, potassium and water are absorbed in the distal convoluted tubule under the influence of aldosterone & ADH
LOTS OF WORK - 10Net Filtration Pressure (NFP)Is the sum of opposing forces
1. glomerular hydrostatic pressure -
the pressure coming into the bowman’s capsule then we have two opposing
2. capsular hydrostatic pressure -
due to the wall of the capsule and the fluid already in the renal tubule and then the other opposing forces the
3. blood colloidal osmotic pressure -
due to the proteins that are already present in the capsular space - 11Golmerular Filtration Rate (GFR) ElaborateThe glomerular hydrostatic (blood) pressure is the major factor forcing fluids out of the blood
this pressure has to overcome the colloid osmotic pressure and the capsular hydrostatic pressure – Factors determining GFR are:
1. Total surface area available for filtration - number of nephrons
2. Filtration membrane permeability (can change)
3. Net filtration pressure
glomerular blood hydrostatic pressure minus the combined pressure of the osmotic and capsular hydrostatic pressure - 12What does normal GFR depend on?Blood flow and pressure - changes in BP either decrease or increase nephrons ability to make a filtrate
- 13Hypertension: Effects on GFRmay impair blood flow to the kidney (hypertrophy of the smooth muscles in the afferent arterioles) reducing the lumen and therefore the blood flow
can also cause damage to the endothelium that accelerates the progress of atherosclerosis, which can ↓lumen of the blood vessels and therefore ↓blood supply to kidneys - 14Why is BP important in GFRKidneys receive 20-25% of the cardiac output to provide enough plasma for high rates of glomerular filtration needed for regulation of body fluid volumes
- 15Hypotension & GFRHypotension leads to lower blood flow to the kidneys - Decreased renal blood flow can result in:
o oliguria (<300-500ml/day) OR
o anuria (<50ml/day)
decreased renal blood flow decreases the work of the kidney & therefore also O2 requirements of cells BUT blood flow below 20% of normal does not meet O2 requirements at rest and renal cells die - 16Acute Kidney Injury (AKI) overviewis an abrupt decrease or cessation of GFR or kidneys stop working
o is REVERSIBLE if the patient gets correct and prompt treatment - 17What are the 3 types of kidney injury (AKI)Pre-renal (55% cases)
Renal (40% cases)
Post renal (5% cases) - 18AKI - Pre Renal- Pre-renal (55% of cases): causes before blood reaches kidney, mostly associated with lack of blood supply/ low BP – hypoperfusion - prerenal acute kidney injury can lead to intrinsic acute kidney injury if it isn't treated promptly
Potential causes:
Haemorrhage, extensive burns, severe vomiting &/or diarrhoea, cardiac failure, septic shock - 19AKI - RenalAlso known as intrarenal or intrinsic
affects nephrons directly, prevents proper filtration of blood and or production of urine - parenchymal damage - 20AKI - Renal further classificationsglomerular, interstitial, tubular & Vascular
- 21AKI - Renal (caused by overview)Caused by nephrotoxic agents & can also be caused by interstitial diseases, infections & vascular diseases
- 22AKI - Renal (potential causes)ischaemia (i.e. pre-renal if severe & prolonged), TOXINS heavy metals e.g. mercury, uranium, arsenic, lead, organic solvents e.g. carbon tetrachloride, radiographic contrast media, myoglobin (from excess rhabdomyolysis), drugs e.g. aminoglycosides, cephalosporins (antibiotics common cause)
o acute glomerulonephritis
o transfusion reactions
o toxaemia of pregnancy
o transplant rejection
o SLE, Goodpasture’s syndrome - 23AKI - Post-renaloriginates beyond nephron but within urinary tract it affects urine movement out of the kidneys, mostly due to back pressure due to obstructions
post renal acute kidney injury is usually characterized by low urine volume or increased urine frequency accompanied by low volumes - 24AKI - Post-renal (potential causes)o Prostatic hypertrophy (benign or malignant),
o Bilateral ureteric obstruction (e.g. calculi, tumours, clots, sloughed papillae)
o Surgical accident
o Ruptured bladder
o Retroperitoneal fibrosis
o External tumours - 25Causes of Acute Kidney Injury (Overall)Complications of surgery, severe burns, trauma
Renal ischaemia caused by blood clots, hypovolemia
Drugs (antibiotics-gentamycin, streptomycin, NSAID, aspirin, ibuprofen)
Toxins (heavy metals, alcohol)
Heatstroke
Multiple organ failure
Sepsis
Obstructed urine flow
Kidney stones
Acute pyelonephritis - 26Kidney stones (renal Lithaisis) CausesDiet or low fluid intake (results in concentrated urine) OR UTI + genetics
Usually calcium (high calcium diets predispose as well has foods containing oxalic acid such as rhubarb)
Stones made of minerals + acid salts, form in kidney and travel down Urinary tract - 27Pyelonephritis (what is it & symptoms)Bacterial infection in the kidney, either from an ascending UTI (travelling up) or via the bloodstream
Fever, pain, nausea (usually develop in a day or less)
Commonly find RBC, WBC, bacteria, and protein in the urine - Can progress to septic shock if left untreated
- More common in women (shorter urethra) - 28The 4 Phases of Acute Kidney Injury (AKI)1. Onset
2. Oliguric
3. Diuretic
4. Recovery - 29AKI - Onset Stagelasts hours or days
time from exposure or event until tubular damage occurs - 30AKI - Oliguric stageDecreased urine output due to decreased GFR
o severe deficiency → ANURIA (<50 ml / 24 hours)
o Build-up of endogenous metabolites (e.g., urea, creatinine)
o Fluid retention edema if prolonged hypertension
o Lasts 8-14 days (or longer) - 31AKI - Diuretic stageas kidneys try to heal
o Filtration is increased but absorption is impaired
o GFR↑, urine output ↑ (waste products in blood slowly removed over time)
o Blood urea, creatinine, etc remain elevated for a time
o Electrolytes may be depleted due to absorption impairment - 32AKI - Recovery stageGradual return to normal
o Normalisation of fluid & electrolyte balance
o Concentrating abilities improves
o Blood urea, creatinine etc return to normal levels
Overall - permanent mild-mod damage to kidney may have occurred - 33AKI - TreatmentFirst line of treatment is if possible – remove cause
- Stop nephrotoxic drugs
- Provide IV fluids - 34Why are hydration status & renal functions carried out prior to an angiogram?Radiocontrast agents used for angiograms are nephrotoxic – those who are at the greatest risk of AKI often receive Iv fluids both before and after the procedure
- 35Chronic Kidney Disease (CKD) overviewProgressive & IRREVERSIBLE decline in GFR
Requires presence of kidney damage or decreased function for ≥3months - 36Chronic Kidney Disease (CKD): CausesDiabetes, hypertension (key risk factors)
Obstructive nephropathy *caused by kidney stones or prostate tumour
Kidney disease, renal artery stenosis, lead poisoning, fatty plaque deposits (atherosclerosis in kidney artery) - 37Types of Chronic Kidney Disease (CKD)3 groups
PRE_RENAL (shock, ischaemia)
RENAL/INTRINSIC (direct damage to nephrons due to infection or nephrotoxic injury)
POST-RENAL (Increased hydrostatic pressure in Bowmans capsule, slow filtration due to obstruction of ureters or blockage of ureters) - 38Chronic Hypertension & CKDKidney VERY sensitive to high BP, elevated BP damages BVs leading to inflammation, thickening of arterial walls and renal ischaemia
- 39Left-sided heart failure & CKDDecreased blood circulation causes inadequate kidney perfusion, waste products accumulate.
GFR maintained at arterial BP of 80-180
below 80 = GFR decreases
Below 40 = GFR stops entirely - 403 stages of Chronic Kidney Disease1. DIMINISHED RENAL RESERVE
2. RENAL INSUFFICIENCY
3. END STAGE - 41Stages of CKD: Diminished renal reserveno signs & symptoms
- 42Stages of CKD: Renal insufficiencyWaste products build up in blood, inability to concentrate or dilute urine, 75% or more nephrons are lost - symptoms likely present
- 43Stages of CKD: End stageOliguria present (low urine output), wast products build up in blood, treatment required to remove excess fluid & waste from blood, 90% or more nephrons lost
- 44What is the issue with kidney disease identification?There is a lack in biochemical markers that identify kidney disease
- 45Most common causes of CKD in NZDiabetes (50% who start dialysis & 25% who get a kidney transplant have diabetes)
High BP (Highly associated with CVD, ~ people with kidney failure die because of CVD) - 46Other causes of CKD in NZRhabdomyolysis (significant muscle damage)
Chronic analgesic nephropathy
Polycystic kidney disease
Kidney stones
Kidney infection
Enlarged prostate - 47What is RhabdomyolysisSignificant muscle damage (e.g. crushed in car accident)
- 48What symptoms arise due to rhabdomyolysis and whynausea, vomiting & confusion due to electrolyte imbalances caused by muscle components (e.g. myoglobin) being released into blood
GFR falls, Urine production decreased & appears red due to myoglobin
Muscle damage leads to high Plasma K+ and low plasma Ca+
Low BP & uric acid crystallisation further destroys tubules - 49Chronic Analgesic nephropathy: what is it caused byDue to long term ingestions of a combinations of analgesics such as acetaminophen, aspirin and non-steroidal anti-inflammatory (NSAIDs)
- 50Chronic Analgesic nephropathy: NSAIDs effectNSAIDs inhibit cyclooxygenases, required to produce prostaglandins
Prostaglandin E2 is produced by the kidney and ensures adequate blood flow to the kidney, decreased blood flow results in damage in the most sensitive area, the inner medulla (interstitial nephritis) and renal papillae (renal papillary necrosis) - 51Polycystic Kidney Disease: what is it & causeGenetic disease, usually autosomal dominant
Multiple (poly) fluid-filled cysts grow out of nephrons; cysts may also be present in spleen and/or liver, Usually bilateral (both kidneys) Cysts gradually replace normal structure
Results: Reduced kidney function, High blood pressure, Eventual kidney failure
(in full-blown PKD, each kidney can weigh over 10 kg!) - 52Enlarged prostate: What is it and its effectprostate wraps around the urethra, Enlarged prostate squeezes the urethra and blocks the flow of urine, Benign enlarged prostate is common
o 60% of men over 60yrs; 80% of men over 80yrs
Initial diagnosis usually from urine not flowing properly = interrupted stream, slowed stream, discomfort
High pressure in the bladder due to urinary retention leads to Pressure damages kidneys (and/or allows bladder infections to reach the kidneys) (back pressure)
- Can lead to chronic kidney disease - 53Normal Urine should be & contain:Clear, amber colour
95% water, 5% dissolved solids
contain metabolic waste - 54Urine should NOT contain:should NOT contain protein, blood or glucose
- 55Urine as a renal function test: CompositionCloudy could be crystals of bacteria
pinky red may have blood (or beetroot)
protein presence & low albumin indicate abnormal filtering or reabsorption defect - 56Urine as a renal function test: Urine specific gravityUrine specific gravity indicates the kidneys ability to concentrate urine
o normal usg is in the range of 1.002 to 1.03 with higher numbers indicating dehydration
o If someone has a usg of <1.002 either they have lost ability to concentrate urine or they are very well hydrated - 57Blood test as renal function testBlood samples can be tested for Blood Urea Nitrogen (BUN) to see if nitrogenous waste in blood - if the GFR rate decreases, BUN increases due to the kidneys being unable to effectively clear nitrogenous waste products from the blood
But also influenced by protein intake
- Plasma creatinine – an increase indicates poor renal function and decreased eGFR - 5824 hr urine samples are used to:calculate GFR
- 59Renal function test: GFR equation & how its calculatedCalculated by measuring any chemical that has a steady level in the blood, & is freely filtered, but neither reabsorbed nor secreted by the kidneys, is the quantity of the substance in the urine that originated from a calculable volume of blood
GFR = Urine concentration x Urine flow ÷ Plasma concentration - 60Renal function: Not often done GFR testsmost accurately measured by injecting an inert polysaccharide, inulin, into bloodstream. Rate of excretion is directly proportional to the rate of filtration of water and solutes across the glomerular filter (not often done anymore)
- GFR can be estimated from creatinine clearance carried out on a 24hr urine sample (not often done anymore) - 61Creatinine & renal functioning24hr container: Creatinine is produced naturally by the body & is freely filtered by the glomerulus, BUT also actively secreted by the peritubular capillaries in very small amounts Resulting in creatinine clearance overestimating actual GFR by 10- 20%
- Ease of measurement makes this inaccuracy acceptable - 6224hr GFR creatinine & renal functionAverage free living person, collecting all urine over 24hr period not very convenient – most commonly done in hospital setting
o Inaccuracies of 24hr urine collection can also occur if fails to totally empty bladder - 63Diagnosis & screening for renal disease: 3 reasons patients generally present1. Abnormality on routine blood test or urinalysis
2. A symptom or physical sign
3. Presence of systemic disease with renal involvement
- Knowledge of clinical history is an important aid in diagnosis and treatment - 64Diagnosis & screening for renal disease: UrinalysisDipsticks often used to concurrently screen for multiple analytes, Presence of specific compounds can indicate cause (e.g. haematuria may indicate glomerular nephritis, polycystic kidney disease etc)
- Microscopic exam
o Presence of casts, crystals and bacteria - 65Diagnosis & screening for renal disease: eGFR monitored over timeIf reduced suddenly, indicative of acute kidney injury (AKI)
If reduced over 3 month period indicates chronic kidney disease (CKD) and staging is commenced - 66Why does a normal GFR not rule out renal disease:NOTE: blood urea nitrogen and creatinine will not be raised above the normal range until 60-75% of total kidney function is lost
Also check for albuminuria and proteinuria as leakage of plasma proteins into the urine is a sign of kidney damage - 67CAPD (Continuous Ambulatory peritoneal dialysis) treatment for renal failure - processCatheter surgically placed in peritoneal cavity, dialysis solution is connected to the catheter fluid is allowed to flow into the cavity Takes ~30-40 mins
during this time the person can sit and do something quietly or they may sleep
once bag is empty it's disconnected, and the catheter is capped
- the person can then go about their normal daily activities
while the dialysis solution is inside the peritoneum it absorbs wastes and extra fluids from the body this.
This period called the dwell time and it usually lasts four to six hours
the solution containing the wastes is then drained into an empty bag and the person starts over with a new bag of exchange solution
because the dialysis process is faster when the fluid is fresher the patient will normally perform four to six exchanges each day and sleep with the fluid in the peritoneum at night - 68Haemodialysis - treatment for renal failure - processA fistula surgically created in arm for access BVs to remove and return blood
temporary catheters can also be used
blood is pumped through the dialyzer which removes waste products in extra fluids and the cleaned blood is returned to the patient's body
process takes 3-5hrs and is performed ~3x/week
- the person is limited to activities which can be performed while sitting or sleeping - 69Treatment for Renal failure: Kidney transplantsuitable donor is needed so the tissues and blood group match
third (donated) kidney is transplanted in the abdominal cavity
regular checks for rejection of the kidney and for function are needed for the duration of the life span of the donor kidney & immunosuppressive medication such as prednisone and cyclosporine - 70Diet intervention when on dialysis- Decreased fluid intake- replace insensible loss only
- Decreased sodium
- Decreased potassium
- Decreased protein
- Adequate carbohydrate/ calorie intake - 71What waste products can build up in people with CKD and whats the result of that?SALT (NaCl) can increase blood pressure, increased thirst, making it more difficult for patients to restrict their fluid intake
POTASSIUM (K) a mineral found in the cells of body tissue , excess would normally be removed by the kidneys
o too high a level of K is bad for the heart (can cause cardiac arrest) - 72Patients with end-stage kidney disease may lack some nutrients, incl:PROTEIN (essential for muscle growth, low levels may increase fluid retention and reduce bodies ability to fight infection)
VITAMINS (some may need Vit B & C supplements) IRON (anaemia) - 73Phosphate levels (Kidney disease)Healthy body keeps phosphate & Calcium in balance
high phosphate levels may be associated with itch and can damage BV in long term - difficult to remove if kidneys failing - phosphate levels will increase, binding to calcium and decreasing calcium levels - 74Calcium levels (kidney disease)- Kidneys produce the active form of vitamin D, this will be reduced when kidneys fail = less calcium absorbed from the gut
High urea levels suppress vitamin D action in the gut = Less calcium absorbed - 75Why can kidney disease lead to osteoperosisdecreased calcium levels
parathyroid levels will increase and calcium will be released from bone leading to osteoporosis
Vitamin D can be administered to help prevent this - 76Hypocalcaemia (Renal failure)Hypocalcaemia causes:
increased capillary permeability neuromuscular excitability, decreases blood coagulation , if severe, tetany can result
Chvostek’s sign: contraction of facial muscle in response to light tap on facial nerve
Trousseau’s sign: carpal spasm induced by inflating a blood pressure cuff - 77Anaemia (renal failure)Anaemia can develop due to low erythropoietin (EPO) levels, & deficiencies in iron & folate = treatment with each of these can be effective
Platelet abnormalities may lead to bleeding (and in turn aggravate anaemia)
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- Fichas sobre Renal Disorders , creado por Ella Glynn el 15/06/2022.
- Creado por
- Ella Glynn · jun 2022
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- 16 jun 2022
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