Renal Function PDF

126 2. Lithium 4. Cr eatinine clearance= a. Used to treat bipolar disorders b. Methods U creat x Volume 24 hr. Urine {ml} ❖ ISEs...

126 2. Lithium 4. Cr eatinine clearance= a. Used to treat bipolar disorders b. Methods U creat x Volume 24 hr. Urine {ml} ❖ ISEs P creat 1440 (min/24 hr) ❖ A tomic absorption BRONCHOOILATORS Creatinine clearance is expressed in mlJmin 1. Theophylline To correct for body surface area: a. Signs of toxicity include nausea, vomiting, headache, ir ritability, Creot Clear x l.73 insomnia Area (nomogram) b. Severe toxicity can cause cardiac arrhythmias, seizures and death 5. eGFR (es timated glomerular filtration rate) c. Caffeine i s active metabolite in a. More sensitive than creatinine neonates (monitor levels) clearance d. Methods b. 2 different equations (MDRD and ❖ Immunoassays (separate assays CKD-EPI) use serum cr eatinine, for theophylline and caffeine) demographic info (age, gender, ❖ LC (monitor both theophylline race) and caffeine simultaneously) c. 24-hour urine collection not n eeded d. Ameri can Kidney Foundation 2. Caffeine r ecommendations to assess kidney a. Given to neonates damage e. Values above 60: report as > 60 ml/min IMMUNOSUPPRESSANTS 6. Urine Albumin 1. Generic names a. Use with eGFR to stage and monitor a. Cyclosporine chronic Kidney disease ( CKD) b. Tacrolirrms c. Sirolimus CREATININE d. Mycophenolic Acid (MPA) 1. From cr e atine in muscle 2. Suppress rejection after organ 2. Can also be measured to evaluate renal transplants function; NOT as sen sitive as GFR 3. Often u sed in combination 3. Classic meth od is the Jaffe reaction a. Creatinine reacts with picric acid in 4. Whole blood specimen of choice except alkaline solution to form a red- for MPA (serum or plasma) orange complex that absorbs light at 5. May need multiple samples instead of 490-540 nm trough collection- area under b. Interferents (non-creatinine time/concentration curve r eflects drug chrom agens) include glucose, exposure acetoacetate and ascorbic acid BLOOD UREA NITROGEN (BUN) Renal Function 1. ,+. in impaired renal function GENERAL INFORMATION 2. ,+. in high protein diet 1. All non-protein nitrogens (urea, creatinine, uric acid and ammonia) are ,+. 3. Rises more r apidly than serum creatinine in plasma in r enal impairment; 4. Methods: referred to a s azotemia a. Colorimetric method: urea reacts 2. Best laboratory evaluation when renal with diacetyl monoxime to form a impairment is suspected is glomerular colored complex filtration rate ( GFR) b. Enzymatic method: Urease hydr olyzes urea into ammonia which 3. Creatinine clearance evaluates GFR is mea sured spectrophotometically (more sensitive than BUN or creatinine) or ·with an I SE ❖ Inhibited by the anticoagulant, sodium fluoride  127 ❖ DO NOT use this anticoagulant ❖ Cirrhosis for any enzyme analysis- may ❖ Viral hepatitis inhibit activity b. Impaired renal function ❖ Blood urea is ♦ (,t- excretion into 5. BUN/creatinine ratio is normally about intestine, site of conversion to 10:1-20: 1 ammonia) CYSTATIN C 1. Serum marker for GFR 5. Causes of false ,t. due to specimen collection and handling 2. Small protein produced by most a. Failure to place sample on ice, nucleated cells in a consistent manner, centrifuge and analyze immediately unaffected. by inflammation, gender, (nitrogenous constituents will age, eating habits, or nutritional status metabolize to ammonia) 3. Method= immunoassay b. Poor venipuncture technique URINE ALBUMIN (probing) c. Incompletely filling collection tube 1. Units a. 24 hr collection: mg albumin/24 hrs b. Random sample: mg albumin/ gram creatinine 2. Alhuminuria categories Category Urine albumin Term Specimen Collection for mg/24hr or mg/g creat. Ammonia Analysis A1 < 30 N to mild,+.. A2 30-300 Moderate ,+.. Endocrinology A3 > 300 Severely ,t.. GENERAL 1. Hypothalmus / Pituitary / End Organ URIC ACID System- Hypothalmus produces 1. End product of purine metabolism releasing hormone which stimulates pituitary to produce stimulating 2. ♦ in gout, renal failure, leukemia, and hormone that causes end organ to chemotherapy treatment produce hormones or initiate a process 3. Colorimetric method (see table page 128) a. Uric acid reduces phosphotungstic 2. Hyper and hypo conditions: end acid to tungsten blue measured product hormone is ♦ (hyper) or t spectrophotometrically (hypo) b. Interferents include lipids and a. Primary caused by end organ several drugs problem b. Secondary caused by pituitary 4. Enzymatic assays are based on the problem uricase reaction in which allantoin and c. T ertiary caused by hypothalmic H 2O2 are produced and H 2O2 is problem coupled to give a colored product AMMONIA 3. Regulation - end organ product or process feeds back to hypothalmus and 1. Derived from action of bacteria on pituitary to stop production of contents of colon r eleasing and stimulating hormones 2. Metabolized by liver normally THYROID HORMONES 1. Stimulate metabolic processes; 3. ,t. plasma ammonia toxic to the CNS necessary for normal growth and 4. Hyperammonemia ( ♦ ammonia) development a. Advanced liver disease (most 2. In the tissues T 4 is converted to T 3 common cause) (physiologically active product): T4 ❖ R eye~syndrome concentration much higher than T3