Renal Flashcards
Protein Restriction, CKD Patients Not on Dialysis and Without Diabetes
- a low-protein diet providing 0.55–0.60 g dietary protein/kg body weight/day, or
- a very low-protein diet providing 0.28–0.43 g dietary protein/kg body weight/day with additional keto acid/amino acid analogs to meet protein requirements (0.55–0.60 g/kg body weight/day)
Protein Restriction, CKD Patients Not on Dialysis and With Diabetes
In the adult with CKD 3-5 and who has diabetes, it is reasonable to prescribe, under close clinical supervision, a dietary protein intake of 0.6-0.8 g/kg body weight per day to maintain a stable nutritional status and optimize glycemic control.
Dietary Protein Intake, MHD and PD Patients Without Diabetes
In adults with CKD 5D on MHD (1C) or PD (OPINION) who are metabolically stable, we recommend prescribing a dietary protein intake of 1.0-1.2 g/kg body weight per day to maintain a stable nutritional status.
Dietary Protein Intake, Maintenance Hemodialysis and Peritoneal Dialysis Patients With Diabetes
In adults with CKD 5D and who have diabetes, it is reasonable to prescribe a dietary protein intake of 1.0-1.2 g/kg body weight per day to maintain a stable nutritional status. For patients at risk of hyper- and/or hypoglycemia, higher levels of dietary protein intake may need to be considered to maintain glycemic control
functions of kidney
Maintain of homeostasis (→regulate blood content) • Control of fluid (water) • pH • Electrolyte balance • Blood pressure
Excretion of metabolic end products (→remove waste) ** most important function
• Filtering waste products from metabolic processes
• Urea and excess water from blood excreted as urine
Production of enzymes and hormones
• Renin (blood pressure): decreased blood flow-> renin production will be triggered to increase water reabsorption to increase pressure
• Erythropoeitin (Red Blood Cell synthesis)
• Vitaimin D (Ca absorption, bone health, muscle contractions)
Which particles can pass through walls of glomerulus?
Walls of glomerulus permit the free flow of water soluble materials (e.g., blood cells and large protein molecules remaining in the blood)
What is glomerular filtrate?
the fluid that enters the Bowman’s capsule (contains waste products like urea, and needed materials like glucose)
how does glomerulus differentiate what should it pass out and what it shouldn’t?
Glomerular filter discriminates on the basis of Size and Charge
What can GFR be used as an estimation of?
Glomerular filtration rate (GFR)
What is GFR?
Expression of the quantity of glomerular filtrate formed each minute in the nephrons of both kidneys, calculated by measuring the clearance of specific substances (inulin or creatinine)
What is usually used for GFR estimation: inulin or creatinine?
inulin is usually harder to assess, thus we usually assess the creatinine
How does GFR compare across ages and genders?
older people and women have lower GFR
WHat is the normal eGFR
eGFR = normal; 90‐120 ml/min/173m^2
Which substances are filtered? which are excluded?
Substances ‘Filtered’: Water, electrolytes (Na, K, etc,) glucose, nitrogenous waste (urea, creatinine) …
Substances ‘Excluded’: Substances of size > 70 kDa Plasma protein bound substances
Which factors can affect serum creatinine levels
- Amount of protein in the diet
- Age
- Muscle breakdown
- Antibiotics inhibit secretion
- Levels are prone to calibration bias
Estimating creatinine clearance: MDRD
Modification of Diet in Renal Disease Equation =
eGFR (mL/min/1.73 m2) =
175 × (Scr)-1.154 × (age)-0.203 × 0.742 (if female) × 1.212 (if black)
Using conventional unit
175 × (Scr/88.4)-1.154 × (Age)-0.203 × (0.742 if female) × (1.212 if African American) (SI units)
- uses 4 values
- adjust for age, gender and ethnicity
- The equation does not require weight because the results are reported normalized to 1.73 m2 body surface area, which is an accepted average adult surface area.
Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) vs MDRD accuracy
- More accurate than MDRD if eGFR >60 mL/min/1.73 m2
* As accurate as MDRD if eGFR < 60 mL/min/1.73 m2
What does CKD-EPI adjust for?
- gender and ethnicity
when does CKD-EPI over and under estimate?
- Surestimation : low IMC
* Underestimation: patients with muscular hypertrophie
WHat are the 3 types and chareactersitics of kidney disease?
Chronic Kidney disease (CKD)
- Slow decrease in function
• Decrease ability to filter blood
• diabetes is the main cause; HTN is the next cause
End-stage renal disease: stage 5- requires hemodialysis
Acute kidney injury (AKI)
• may be reversible
• Sudden damage to the kidneys that causes loss of function- occurs over hours or days
- damage may occur before or after the kidney
how is the amount of urea produced affected when there are kidney problems?
less will be produced
what is the consequence of decreased GFR?
• If decrease GFR→urea cannot be excreted and build up in the blood
-> azotemia
• General symptoms: Nausea, Loss of appetite
• Encephalopathy: Asterixis (tremor of the hand), Coma and death
- Pericarditis
- Bleeding (less clot formation • Uremic frost
Potassium and decreased GFR interconnection
If decrease GFR → Hyperkalemia → Cardiac arrythmias
Calcium and kidney problems interconnection
Less activation of Vitamin D by Kidney→ lowered Ca2+ absorption from diet →Hypocalcemia
→If Ca decrease→ Parathyroid hormone is release→ Bones lose Ca2+ →The loss of Ca2+ by bones can lead to renal osteodystrophy
hormones and kidney problems interconnection
• Renin (secreted by kidneys):
If low fluid rate –> kidney secrete renin to increase blood pressure → Hypertension … (vicious cycle)
HTN will lead to lower kidney function-> lower fluid rate-> renin-> repeaaaat
• Erythropoietin
Decrease EPO production→ lowered production of red blood cells→ Anemia
types of AKI
Acute Kidney Injury – Acute renal failure (AKI - ARF):
- Prerenal
- Postrenal
- Intrarenal
types of CKD
Chronic kidney disease - Chronic Renal Failure (CKD - CRF)
- Chronic renal insufficiency (CRI)
- End stage renal disease (ESRD)
name 4 renal disorders
- Acute kidney injury
- chronic kidney disease- chronic renal failure
- nephrotic syndrome
- urolithiasis
what are the steps of diagnosis of chronic disease?
- Based on CHANGES in GFR over TIME
• Chronic kidney disease: Less than 90ml/min/1.73m^2 for at least 3 months
• Irreversible kidney damage: Less than 60ml/min/1.73m^2 - Biopsy: Glomerulosclerosis- sclerosis is a sign that kidney function is altered
Laboratory Evaluation of Kidney Function
- Microalbuminuria
- GFR-glomerular filtration rate
- Clearance calculations (age,ethnicity,gender)
- Tubular function tests
- Microscopic evaluation of the urine
- Radiologic evaluation(IVP,MRI,ultrasound)
- Biopsy
Kidney disorder treatment
- Manage the underlying cause
- Dialysis
- Transplant
Nutrients of Concern in kidney disorders
- Energy
- Protein: intake has to be decreased in cases of loss of kidney function. intake has to be increased in case of hemodialysis
- Phosphorus • Sodium
- Potassium
- Calcium
- Fluid: sometimes has to be decreased due to extremely low kidney function-> minimal filtration-> fluid restriction
Potassium restrictions?
• Restriction varies according on the degree of kidney function, serum potassium levels, type of dialysis, drug therapy
In HD or PD blood is filtered every 2 days
Between those 2 days there might be a build up of potassium in blood-> potassium in the diet has to be restricted
• HD: 2-3 g/d
• PD: no restriction, +/- supplement
• Serum potassium : 3.5-6.0 mEq/L
• High potassium and low potassium foods
what are possible non-nutritional causes of hyperkalemia?
GI bleeding, acidosis, hypoaldosteronism
Drugs that may raise potassium
- ACE inhibitors
- ARBs
- Selective Aldosterone Receptor Antagonists (e.g. eplerenone) • Trimethoprim–sulfamethoxazole
- NSAIDs
- Beta Blockers,
- Potassium-sparing diuretics (e.g. amiloride or spironolactone)
- Antifungals(e.g.fluconazole)
Name high and low potassium foods?
High potassium foods
• Fruits (dried apricots, juice, banana, avocado)
• Vegetables such as cooked broccoli and spinach, and potatoes
• Other foods: bran products; chocolat; milk; molasses; nuts and seeds, Salt-free broth, salt substitutes. Yogurt, bran cereals, and cooked halibut
and salmon
Low potassium foods
• Some fruits: apple, berries, grapes, pineapples
• Some vegetables
• Other foods: Rice, noodles, pasta, coffee, tea
Canned fruits usually contain less potassium than fresh fruits. Drain all the fluid before serving
Fluid and sodium reqs
• Needs vary according to urine output
- > If output less than 1L/d: restrict to 1-1.5L and 2g sodium
- > If output greater than 1L/d: 2L and 2-4 g sodium
• Needs vary according to type of dialysis
- Blood pressure control
- Interdialytic weight gains (HD) (should not exceed 5% of BW)
- PD: 1-3 L and 2-3g sodium
- Presence of edema
- Congestive heart failure
• Pre-dialysis no need for fluid restriction/ sodium restriction according to BP
Phosphorus reccs
- If HD and PD: restriction 800-1000 mg/day or < 17 mg/kg of IBW
- Use of phosphate binders to limit GI absorption
Name high phosphorus foods
- Dairy products (cheese, milk, …)
- Protein (livers, oyster, sardines, carp…)
- Vegetables (beans, lentils, chick peas…)
- Other (bran cereals, seeds, whole-grain products, nuts…)
Calcium reccs
- Goal is to maintain serum calcium between 8.4 and 10.2 mg/dl
- Adjusted serum calcium calculation: ((4-albumin mg/dl) X 0.8) + Ca mg/dl
- Should not exceed 2,000 mg/d
- Careful to phosphate-binders
- Use of active Vit D Sterols increases calcium absorption in the intestine
Vitamin supplementation reccs
• Water-soluble vitamins supplement
- > Increased losses during PD and HD; anorexia; poor intake)
- > Diet restrictions
- > Impaired synthesis
• Serum vitamin A are elevated in PD and HD: no need to supplement
Magnesium reccs
- Kidney is main organ responsible for normal maintenance of serum magnesium
- Patients must avoid use of laxatives, enemas or phosphate binders containing magnesium
- Water is a potential source of excessive magnesium
- Check that source of water is low in Mg
Iron reccs
- Iron deficiency is common
* Supplement according serum markers of ferritin, iron, total iron binding capacity and transferrin saturation
Zinc reccs
- Patients undergoing maintenance hemodialysis are known to have decreased levels of zinc in serum, hair, and kidneys
- Researchers suggest that zinc supplementation in the amount of 15mg/d may improve dysgeusia (loss of taste) and may be helpful in the management of impotence in male hemodialysis patients
Selenium reccs
- Selenium has important antioxidant properties but plasma levels are low in hemodialysis patients
- Selenium supplementation has not been studied, there are no recommendations for this population
Antioxidant reccs
- Antioxidants from high nutrient density foods
- Teach patients to use whole grains, deep dark colored fruits and vegetables
- Antioxidants benefit the patient on dialysis in all the same ways that the normal population benefits from the use of foods high in nutrient density
what is nephrotic syndrome?
nephrotic syndrome—a clinical condition consisting of losses of protein in the urine exceeding 3.5 g/day, hyperlipidemia, and low albumin levels (,3.5 g/dL) with edema
is filtrate excreted or reabsorbed?
reabsorbed
kidney problems and metabolic acidosis
Metabolic acidosis increases as a result of the kidneys’ decreased ability to excrete hydrogen ions.
kidney problems and potassium levels
As GFR begins to decline, the excretion rate of potassium increases; however, as renal function continues to decline, this compensatory mechanism can no longer prevent the accumulation of potassium, which ultimately results in hyperkalemia (elevated blood potassium)
renal osteodystrophy
Parathyroid hormone (PTH) also aids in regulating serum calcium by stimulating bone resorption and kidney reabsorption, and by converting the inactive form of vitamin D to the active form (1,25[OH]2D3 ). Deficiency of the active form of vitamin D is associated with impaired intestinal calcium absorption and secondary hyperparathyroidism, both of which contribute to the development of bone and mineral disorders (renal osteodystrophy).
what are the leading causes of kidney failure?
diabetes, hypertension, and glomerulonephritis
potential causes of and risk factors for CKD
- Ethnicity—African Americans are nearly four times as likely to develop kidney failure as white Americans; Native Americans are nearly two times as likely, and Hispanic Americans have nearly twice the risk of non-Hispanic whites
- Family history—CKD runs in families, so one’s risk is greater if a family member has kidney failure
- Hereditary factors such as polycystic kidney disease (PKD)
- A direct and forceful blow to the kidneys
- Prolonged consumption of over-the-counter painkillers that combine aspirin, acetaminophen, and other medicines such as ibuprofen