| A | B |
|---|
| Urea comprises this amount of the NPN | about half of the total NPN |
| Most common individually measured elements of NPN are | Urea, Creatinine, Creatine, Ammonia and Uric Acid |
| The US expresses urea as | BUN (Blood Urea Nitrogen) |
| BUN can be converted to the European Urea by | multiplying BUN by 2.14 |
| Liver synthesizes urea from | CO2 & ammonia arising from the breakdown of amino acids |
| Filters NPN substances from the blood | glomeruli in the kidney |
| Increased urea (BUN) in the blood is called | azotemia |
| Very increased blood urea (azotemia) with renal disease | Uremia or Uremic Syndrome |
| Reference range for urea | 6-20 mg/dl |
| Main cause for prerenal increase of blood urea | Congestive heart failure |
| Main cause of renal increase of blood urea | Decreased renal function (glomerulonephritis, tubular necrosis, etc.) |
| Main cause for postrenal increase of blood urea | Obstruction of urinary flow caused by stones, tumors, UTI's |
| Enzyme used to measure Urea | Urease |
| Ways to measure ammonium after using urease to break down urea | pH indicator (measures alkalinity of ammonium), enzymatic (gldh), or conductivity (ionic NH4+) |
| The best way to check the accuracy of a 24 hour urine collection | measure the urine creatinine |
| Two NPN subances that indicate renal disease | increased plasma creatinine and urea (BUN) |
| Normal BUN to creatinine ratio | 10:1 to 15:1 or 20:1 |
| Creatinine is made from | Creatine in the muscle (or creatine phosphate) |
| Method to measure creatinine ; uses alkaline picric acid | Jaffe' method |
| Interferences of the Jaffe' method | ascorbic acid, acetone (ketones), cephalosporins, glucose |
| Methods used to improve specificity of the Jaffe' method | Protein-free filtrate with or without Fuller's earth adsorbent or Kinetic measurement |
| The enzymatic method for measuring creatinine | Coupled enzymatic method using creatininase, measures H2O2 formed with peroxidase |
| Plasma creatine increases and creatinine is normal in | Muscular Dystrophy and poliomyelitis |
| Uric acid is the final breakdown product of | purine metabolism of DNA & RNA |
| Increased uric acid levels in the plasma | Seen with Gout, Lesch-Nyhan Syndrome, chemotherapy, renal disease |
| Caraway method of measuring Uric acid | uric acid oxidizes to allantoin and phosphotungtic acid reduces to tungsten blue |
| uricase method of measuring uric acid measures | H2O2 formed with an enzymatic procedure (either peroxidase or catalase) or measures absorbance before and after adding uricase |
| Reference range for Creatinine | 0.5 - 1.2 mg/dl |
| Reference range for Ammonia (NH3) | 15 - 45 ug/dl |
| Made from the deamination of amino acids by digestive enzymes/bacteria | Ammonia |
| If the liver is diseased (Hepatic failure)... | Ammonia levels in the blood will rise |
| Syndrome where ammonia levels are increased | Reye's Syndrome |
| Blood samples collected for ammonia must be... | Iced and have plasma removed ASAP |
| Sources of ammonia contamination in a blood sample | Tobacco smoke, urine, NH3 from glassware, detergents, reagents, and water |
| Methods for measurine ammonia include | GLDH enzymatic assays, ISE, and PH indicator such as brophenol blue |
| Uricase breaks down uric acid to | allantoin and H2O2 |
| When NADH is changed to NAD+ | there is a decrease in absorbance as it is oxidized to NAD+ |
| Anticoagulant can't be used for the urease method | sodium floride |
