Post on 12-Jan-2016
Urea and electrolytes
Resources
Common Patterns of Water and Electrolyte Change in Injury, Surgery and Disease
(Moore, NEJM 1958)Fluid, Electrolyte, and Acid-Base emergencies (Morris,
in Current Diagnosis and Treatment series, 2008)Approach to Fluid and Electrolyte Disorders and Acid-Base Problems
(Palmer, 2008) Oxford Handbook of Clinical Medicine 8e, p678
Normal, abnormal, and Dangerous results
“Normal” range Danger limits Units
Na+ 135 – 145 120 – 155 mmol/L
K+ 3.5 – 5 2.5 – 6.5 mmol/L
Total Ca++ 2.12 – 2.65 mmol/L
Corrected Ca++ 2.0 – 3.5 mmol/L
Glucose 3.5 – 5.5 2.0 – 20 mmol/L
Total Ca++ is measured, but unbound Ca++ is the important factor.Albumin below 40g/L: add 0.1 mmol/L to Ca++ for each 4 g/L albumin drop.
Oxford handbook of clinical medicine, p679
Relative limits
Na+
K+
Corrected Ca++
Glucose
0 50 100 150 200 250 300 350 400 450 500
Steps
1. Sodium relative to osmolarity2. Chloride relative to sodium3. Anion Gap ([Na] – [Cl] – [HCO3]) and pH4. Potassium
Approach to Fluid and Electrolyte Disorders and Acid-Base Problems (Palmer, 2008)
5. Urea, creatinine, urea to creatinine ratio, gfr
Anion GapCations (t = +) Anions (n = negative)
Na+ Cl-
K+ HCO3-
H+ Albumin
Ca++ Lactate
Mg++ Urate
Proteins Phosphate
Sulphate
Ketone bodies
Proteins
Patterns?Tubular damage Addison’s diseaseGlomerular damage Cushing syndromeLactic acidosis Diabetes MellitusKetoacidosis Diabetes InsipidusDehydration Bone disordersGIT upset SIADHDiuretics Other drugs
Oxford handbook of medicine 8e
Kidney patterns
Low GFR Tubular dysfunction
Thiazide and Loop Diuretics
Urea ↑ - ↑
Creatinine ↑ -
Na+ ↓
K+ ↑ ↓ ↑
H+ ↑ ↓
HCO3- ↓ ↑ ↑
Anion Gap ↑
Ca+ ↓
Urate ↑ ↓
Phosphate ↑