PHAR 505- Kidneys

Kidneys

-Remove waste/toxins (BUN SrCr)

-Major drug route elimination

-Maintain chemical homeostasis

-Produce hormones (calcitriol, renin, erythropoietin)

-Maintain blood pressure

-Keep bones healthy

Nephron

1. Glomerular filtrate

2. Reabsorption from tubules

3. Secretion from blood and tubule cells

4. Excretion through urine

RAS

-AG II: Renin activates to low kidney blood flow. Arteriolar vasoconstriction and increased volume by sodium and water reabsorption. Increased blood pressure.

-AG II helps with glomerular filtration and kidney blood flow.

Chronic Kidney Disease (CKD)

-Kidneys lose ability to filter waste and excess fluid from blood

Chronic Kidney Disease (CKD) Leads to

-Anemia

-Mineral and bone disorder

-Electrolyte disorders (Na, K)

-Fluid overload (hyperfiltration)

-Metabolic acidosis

-CVD

-Foamy urine

-ACR of >30 for 3 months

-GFR <60 ml/min

Chronic Kidney Disease (CKD) Risk Factors

-Hypertension

-Diabetes

-CVD

-HF

-Prior AKI/AKD

Acute Kidney Injury (AKI)

-Rapid (days to weeks) deterioration of kidney function

-Increase Scr and/or decrease urine output

-Decrease blood flow to kidney, damage to glomerulus, tubule, or interstitium, obstructed urine flow

AKI Risk Factors and Complecations

-Risk Factors: Age, hypertension, diabetes, metabolic syndrome, HF, CKD, medications

-Usually reversable, can lead to CKD

-Can lead to kidney failure if severe

-AKI is an independent predictor of mortality and CVD

AKI Stage 1

-Increased Cr x 1.5 or >0.3 mg/dl

-Urine output <0.5 ml/kg/hr x 6hr

Prerenal AKI

-Decrease blood flow to kidney

-Decrease cardiac output

-SNS activation

-RAS activation

Intrarenal AKI

-Damage to glomerulus, tubule, or interstitium

-Decrease renal blood flow

-RAS activation

Postrenal AKI

-Obstructed urine flow

Kidney Disfunction Assessment

1. Symptoms depends on cause

2. May present with some or all typical signs

3. May present with NO symptoms, can detect through blood and urine testing

4. CKD and AKI have similar symptoms, so look at timing of symptoms

5. Some signs/symptoms are shared with other disease, so not always kidney disfunction

Symptoms for Kidney Disfunction

-Change in urine output (decrease most likely)

-Bubbly/foamy urine from protein/albumin

-Change in weight from swelling (edema, excess water, malnutrition)

-Change in blood pressure (NSAID, disease)

-Leg swelling, muscle cramps, nausea/vomiting, shortness of breath, itchy skin, fatigue)

Indices of Kidney Disfunction

-Increase BUN

-Increase Scr

-Increase cys c

-Albumin in urine

-Urine albumin:creatinine ratio >30-300

Kidney Assessment for Drug Dosing

-eGFR/eCLcr

-Use race free CKD-EPI equations

Maintain Osmotic Equlibrium (Vasopressin)

-Activated by decrease in plasma volume

-Inhibited by Increase in plasma volume

-Puts water back into body to normalize osmolality

Volume Disorders

-Hypovolemia: Water and salt loss. Tachycardia, low bp, thirst, dry mouth, dizziness, water weight loss, pale dry skin.

-Hypervolemia: Salt retention, decreased water loss. Swelling, edemia.

-Euvolemia: Normal

Hyponatremia

-Too much water intake compared to excretion

1. too much water ingested

2. Ingesting water with kidney failure

3. Ingesting normal amounts of water in presence of AVP

-Causes: Heart failure, liver failure (cirrhosis)

(Na+ < 135 mEq/L)

Hypernatremia

-Gain of sodium or loss of water that can’t be replenished (Na+ > 145 mEq/L)

Potassium Disorders

-Hypokalemia: Decreased intake of potassium. Increased loss. (K+ < 3.5 mEq/L)

Hyperkalemia: Increased intake of potassium. (K+ > 5 mEq/L)