Renal Disorders Flashcards
1
Q
What is the functions of the kidneys?
A
- Regulates water and electrolyte balance
- Excretes metabolic waste products and foreign substances
- Conserves nutrients
- Secretes erythropoietin for the production of red blood cells
- Has a role in the control of BP through the renin-angiotensin-aldosterone system with the regulation of sodium and water balance
- Converts Vitamin D into an active form
- Regulates acid base balance by the urinary output of hydrogen and bicarbonate.
2
Q
Urine production
A
- Glomerular filtration
- Selective tubular absorption
- Tubular secretion
- 180 litres of plasma are filtered every day
- 99% of filtrate is reabsorbed by the nephrons
- 1.5 litres of urines are produced every day
3
Q
What is glomerular filtration?
A
- Process were H2O and dissolved substances move across a membrane under pressure
- Afferent arteriole ( is the arteriole that brings blood to the glomerulus) of Bowman’s capsule larger than efferent arteriole ( that carries blood away from the glomerulus.)
- Membrane allows free passage of H2O, solutes and small protein molecules (less than 3mm) but larger molecules such as blood cells and larger protein cannot pass through
- Filters into the proximal tubule
- GFR = 120ml/min
4
Q
Selective Tubular Reabsorption
A
Reclaims useful or necessary substances
- Proximal convoluted tubule = 2/3rds reabsorbed, active reabsorption (glucose, amino acids, Na+, K+, Vit C, phosphate, sulphate) and passive reabsorption (Urea, H20, Cl-), some secretion (Histamine, creatinine, choline, some drugs)
- Loop of Henle = concentrates the urine, descending limb, passive removal of (H20, Na+, Cl-), ascending limb, passive removal (Cl-, Na+)
- Distal convoluted tubule = active reabsorption Na+. K+, ?Cl-, active secretion into lumen K+, passive reabsorption H20 in presence of ADH
5
Q
Tubular secretion
A
- Clears the blood of unwanted substances such as hydrogen ions, ammonia, drugs such as penicillin, urea or excess potassium ions
- Important role in acid base balance
6
Q
Components of the urine
A
- Water 96%
- Urea 2%
- Uric acid
- Creatinine
- Ammonia
- Sodium
- Potassium
- Chlorides
- Phosphates
- Sulphates
- Oxalates
7
Q
Physiological changes to renal in pregnancy
A
- Increase in kidney volume, weight and size Bladder capacity doubles by term to 1000ml
- Under influence of progesterone relaxation of bladder trigone
- Maternal & placental hormones increase plasma volume and alter renal function, > 50%-80% increase in renal blood flow
- Under influence of oestrogen bladder mucosa becomes hyperplastic and increased blood supply = oedematous = more vulnerable to trauma and infection
- The increased blood flow will lead to a 50% increase glomerular filtration rate
8
Q
Changes associated with ↑GFR and tubular function in pregnancy
A
- Increased excretion of solutes including glucose, amino acids, protein, electrolytes and water soluble vitamins, although tubular reabsorption increases to prevent the depletion of essential electrolytes
- Decreased tubular glucose reabsorption means glycosuria is a common finding (good medium for bacteria to grow)
- Sodium filtration is increased but reabsorption increases also resulting in a net retention of sodium
- Excretion of water soluble vitamins increases, so maternal diet needs to include Vit B12, B2, B6 and C, folate and niacin
- Urinary calcium excretion is increased but this is balanced by increased intestinal absorption of calcium
- Increased secretion of urea, creatinine, uric acid and nitrogen in the urine
- Decrease in serum levels of urea, blood urea nitrogen, creatinine and uric acid
- Alteration in renal excretion of drugs
- Renal acid-base balance is altered to compensate for the respiratory alkalosis caused by increased alveolar ventilation with increased renal loss of bicarbonate
9
Q
Anatomic Alterations in Renal Functions in Pregnancy
A
- Renal dilatation due to progesterone -> increases the size of the kidney & ureters leading to a reduction in urinary flow combined with decreased bladder tone= tendency to urinary stasis
- As the uterus enlarges the urinary bladder is displaced and pressure from the uterus obstructs flow of urine
- Change in the angle at which the ureters enter the bladder = urine reflux
- All of these effects predispose women to UTI’s & pyelonephritis
10
Q
Tests
A
- Bacteriological – MSU, CSU
- Biochemical – 24hr urine, determines glomerular filtration rate can look at protein and creatinine clearance
- Haemotological
- Creatinine - waste product produced by muscles and put out through the kidneys
- Urea - Urea is a small molecule that is produced in the liver from protein that you have eaten. It is normally put out by the kidneys, so blood levels rise as kidneys fail
- Uric acid -Uric acid is a chemical created when the body breaks down substances called purines. Purines are found in some foods and drinks, such as liver, anchovies, mackerel, dried beans and peas, beer, and wine. Excreted by the kidneys = ↑= kidney failure- Other related tests
- Sodium (Na) - often too much of it in your body when your kidneys don’t work properly
- Potassium (K) - levels in blood may rise in kidney failure
- Calcium (Ca) – Low in kidney failure
- Other related tests
11
Q
Mechanical problems in pregnancy and puerperium
A
- Frequency
- Incontinence
o Stress incontinence following nerve damage to the pelvic floor
o Urinary retention with overflow
o Vesicovaginal fistula due to obstructed labour/instrumental delivery - Urinary retention
o Bruising/oedema/trauma to the urethra/bladder neck
o Over-distension of the bladder during labour
o Frequent catheterisation in labour
12
Q
Renal disorders
A
- Asymptomatic bacteriuria
- UTI
- Acute pyelonephritis
- Glomerulonephritis
- Nephrotic Syndrome
- Renal Failure
- Acute Kidney Injury (AKI)
- Chronic Kidney Disease (CKD)
- Renal Transplant
13
Q
Asymptomatic Bacteriuria
A
- Defined as bacteriuria with > 100,000 organisms/ml of urine in a clean catch
- A –ve urinalysis for protein not a reliable indicator
- All women screened antenatally at booking
- Associated with low birthweight babies, pre-term birth, hypertension, anaemia and pre-eclampsia
- Treated with antibiotics in order to prevent UTI (40%) or pyelonephritis (25%)
- Education re hygiene
14
Q
UTI
A
- At least 50% of women at some time in their lives will experience a UTI
- Up to 10% of pregnant women will develop a UTI
- usually Eschericia Coli
- Occurs in 2-10% of pregnant women due to pressure of gravid uterus on renal system and relaxing effects of progesterone
- Symptoms – dysuria, offensive smelling urine, urinary frequency, urgency, nocturia and lower back pain (kidneys being inflamed), fever
- Diagnosis = MSU for urine microscopy and culture
- Prompt treatment with AB’s to reduce the risk of developing pyelonephritis
Treatments - Nitrofurantoin 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days, use with caution in 3rd trimester
- Trimethoprim 200 mg twice daily, for 7 days (off–label use), avoid use in first trimester
o Give folic acid 5 mg daily if it is the first trimester of pregnancy.
o Do not give trimethoprim if the woman is folate deficient, taking a folate antagonist, or has been treated with trimethoprim in the past year. - Cefalexin 500 mg twice daily, or 250 mg 6-hourly, for 7 days.
- Cefalexin 250mg OD for recurrent UTI (continuous prophylactic OABX)
- Amoxicillin is also an ABX of choice
- If resistance, then other antibiotics to be discussed with lead microbiologist
15
Q
Acute Pyelonephritis
A
- Inflammation of the kidney due to acute bacterial infection
- Commonly a result of untreated UTI
- Can cause pre-term labour, acute renal failure, septic shock, pulmonary oedema
- Signs & Symptoms
o Sudden onset of severe symptoms
o Right side more commonly affected
o Marked pyrexia (>40ºC), rigors, tachycardia
o Nausea & vomiting
o Frequency & dysuria, pain follows path of ureters
o Oliguria, offensive urine, proteinuria
o Raised CRP
Treatment
- Immediate hospital admission
- Take MSU for culture & sensitivity, FBC
- General nursing care (reduce temperature & comfort measures) & clinical observations
- Pain relief, antipyretics, antiemetics
- Rehydration therapy
- Monitor fluid balance
- Intravenous antibiotics (e.g. penicillins, cephalosporins)
- Monitor uterine activity & fetal condition
- TED prophylaxis = TED’s and anticoagulant therapy
Follow up
- Continue to screen for infection
o Repeat MSU 2 weeks after completion of antibiotics
o Repeat monthly until birth
- If severe/repetitive infection, undertake excretion urography 3 months postpartum to detect abnormality of the renal tract
- Antibiotic prophylaxis, if indicated
