7 - HypoPhosphatemia Flashcards
Normal Serum Phosphorus
2.5 - 4.5
mg/dL
85% found in BONE
14% in INTRAcellular fluid
1% in extracellular
Phosphorus Regulation
KIDNEY
is the most important regulator of serum phos
Maintains a Steady State between:
# Absorbed from INTESTINES : # EXCRETED in URINE
(1/3 in feces – 2/3 in urine)
2step process:
1) Glomerular Filtration
2) Proximal Convuluted Tubular Reabsorption by Passive xport
* INHIBITED* by PTH & CalciTRIOL
* *Increased by GH**
HypoPhosphotemia
INCIDENCE
3% of ALL hospitalized Patients:
70% of ventilated pts in ICU
18% of ICU pts
10% of alcoholic pts
MILD / MODERATE / SEVERE
HypoPhosphatemia
Mild:
<2.5
Moderate:
<1.5
Severe:
<1
Redistribution of Phosphate from
EC Fluid –> Cells
Etiology of HypoPhosphatemia
Stimulation of GLYCOLYSIS –> formation of phos complex
occurs w/
admin of INSULIN or GLUCOSE
acute Respiratory ALKALOSIS
Marked desposition of Ca+ / Phos –> BONE
Hungry Bone Syndrome
+
Refeeding Syndrome
Decreased Intestinal Absorption of Phosphate
Etiology of HypoPhosphatemia
Inadequate Phos Intake
rare due to KIDNEY regulation
can be severe w/ chronic diarrhea / gastric bypass
MEDICATIONS:
Antacids / Phos binders for CKD treatment / Niacin
VITAMIN D DEFICIENCY
Steatorrhea / Chronic Diarrhea
Decreased Intestinal Absorption of Phos
Etiology of HypoPhosphatemia
INcreased URINARY Phos Excretion
from:
1* & 2* HYPERparathyroidism
Primary renal phos Wasting
Proximally Acting Diuretics:
Acetazolamide / Metazolone
Removal by RENAL REPLACEMENT therapies
Etiology of HypoPhosphatemia
Continuou renal replacement therapies = BIGGEST CULPRIT
Always taking AWAY phos / electrolytes
When are Signs & Symptoms of HypoPhosphotemia seen?
Depend on severity / chronicity of phos depletion
Most commonly seen with COMBINED:
Phos Depletion + IntraCellular Shifts
Symptoms are due to:
Consequences of Intracellular Phos Depletion
Phos <1.0
S/Sx of HypoPhosphotemia
Kidney –> HYPERcalciuria
Muscle
Increased Bone Resorption –> Rickets / Osteomalacia
MUSCLE DYSFUNCTION
CNS:
Metabolic Encephalapathy from ATP DEPLETION
Irritability / Parasthesia / Seizures
- *Cardiopulmonary**
- *Ventricular arrhythmias** / diaphragmatic contractlilty
Hematologic Dysfunction
thrombocytopenia / hemolysis
/ diminished fxn of phagocytes+granulocytes
Treatment Goals
HypoPhosphotemia
- *PREVENTION IS NUMBER 1**
- *iatrogenic** –> mainly caused by clinical treatment
Reversal of S/Sx
- *Normalization** of Serum Phos
- *2.5 - 4.5**
Management of Underlying Conditions
Asymptomatic & 1.5-2mg Phos
ORAL TREATMENT
DIETARY SUPPLEMENTATION
of Phos-Rich Foods
(beer/ale / DARK COLA / cheese / liver / chocolate)
1mmol / kg
(Max 80mmol)
if reduced GFR:
1/2 suggested dose
Asymptomatic & 1.0-1.5 mg/dL
DIETARY SUPPLEMENTATION of Phos Rich Foods
(beer/ale / DARK COLA / cheese / liver / chocolate)
1.3 mmol/kg
(Max 100mmol)
if reduced GFR –> 1/2 suggested dose
K-Phos Neutral
Phospha 250 Neutral
Oral Phos Supplements
NEED TO KEEP AN EYE ON POTASSIUM
1.1 mEq of K
All have 250 mg Phos = 8 mmol P
Tablet & Packet
Phos-Na-K Powder
Oral Phos Supplements
NEED TO KEEP AN EYE ON POTASSIUM
7.2 mEq of K
All have 250 mg Phos = 8 mmol P
PACKET ONLY
Neutra-Phos tablet
Oral Phos Supplements
NEED TO KEEP AN EYE ON POTASSIUM
7 mEq of K
All have 250 mg Phos = 8 mmol P
TAB ONLY
PHOS-RICH FOODS
Beverages
•Beer/ale, chocolate drinks, cocoa, dark colas, canned iced teas, dark- type soda (Dr. Pepper), bottled beverages with phosphate additives
Dairy products
•Cheese, liquid nondairy creamer, custard, ice cream, milk, pudding, cream soups, yogurt
Protein
Oysters, sardines, beef liver, chicken liver, fish roe, organ meats, beans
Other
Chocolate candy, caramels, oat bran muffin, most processed/prepared foods, pizza, brewer’s yeast
Oral Phosphorous Supplemnts
MONITORING // ADR
K-Phos Neutral = 1.1 k // Powder = 7.2K // Tab = 7k
Monitor:
Phos + Baseline Calcium
Serum Na +/- K
ADR:
DIARRHEA
HYPERkalemia / HYPERnatremia
extra skeletal calcifications
Indication for
INTRAVENOUS PHOS TREATMENT
SYMPTOMATIC HypoPhosphatemia = < 1mg/dl
or
UNABLE to tolerate PO therapies
VVVVV
Switch to ORAL when Phos > 1.5 mg/dl
TREATMENT
for A/Symptomatic w/ Phos >1.2
Dietary Supplementation of Phos-Rich Foods
- *0.08 - 0.24** mmol/kg
- *over 6 hours**
(max 30mmol)
TREATMENT
for SYMPTOMATIC
w/ Phos <1.2 mg/dL
Dietary Supplementation of Phos-Rich Foods
- *0.25-0.5** mmol/kg
- *over 8-12 hours**
MAX 80 mmol
DOSE ADJUSTMENTS for HIGHER DOSES
HypoPhosphatemia
Acute on Chronic
Chronic > 1 week
DOSE ADJUSTMENTS for Lower doses
HypoPhosphatemia
Ca 10.5-12 –> 50% of dose
Ca >12 mg/dL –> HOLD PHOS
calcifications can occur –> CORRECT CALCIUM FIRST
renal dysfuncions
IV PHOS SUPPLEMENTS
- *SODIUM PHOSPHATE**
- *PREFFERED**, unless also treating K <3.5 mEq/l
Potassium Phosphate
for treating K<3.5
Monitoring for
IV PHOS SUPPLEMENTS
Serum Phos = q6hours
Anticipate a drop in Phos 2 days AFTER
Serum:
Calcium / Magnesium / Na-K
Kidney Function
avoid/reduce dose in renal impariment
ADR
IV PHOS SUPPLEMENTS
Calcium Phosphorous PRECIPITATION in IVPB
deposit in KIDNEY –> RENAL FAILURE
Complications with:
OVER TREATMENT & INCREASED RATE of ADMIN:
Hypocalcemic tetany
EKG changes
HYPERphos / hypoMAG
Treatment in URNARY PHOSPHATE WASTING
difficult to treat
Admin of PHOS –> MORE PHOS EXCRETION
???Dipyridamole???
need more studies, 75mg PO QID
