7 - HypoPhosphatemia

Question 1

Normal Serum Phosphorus

Answer 1

2.5 - 4.5
mg/dL

85% found in BONE

14% in INTRAcellular fluid

1% in extracellular

Question 2

Phosphorus Regulation

Answer 2

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**

Question 3

HypoPhosphotemia
INCIDENCE

Answer 3

3% of ALL hospitalized Patients:

70% of ventilated pts in ICU

18% of ICU pts

10% of alcoholic pts

Question 4

MILD / MODERATE / SEVERE

HypoPhosphatemia

Answer 4

Mild:
<2.5

Moderate:
<1.5

Severe:
<1

Question 5

Redistribution of Phosphate from
EC Fluid –> Cells

Etiology of HypoPhosphatemia

Answer 5

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

Question 6

Decreased Intestinal Absorption of Phosphate

Etiology of HypoPhosphatemia​

Answer 6

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

Question 7

Decreased Intestinal Absorption of Phos

Etiology of HypoPhosphatemia

Answer 7

INcreased URINARY Phos Excretion
from:
1* & 2* HYPERparathyroidism

Primary renal phos Wasting

Proximally Acting Diuretics:
Acetazolamide / Metazolone

Question 8

Removal by RENAL REPLACEMENT therapies

Etiology of HypoPhosphatemia

Answer 8

Continuou renal replacement therapies = BIGGEST CULPRIT

Always taking AWAY phos / electrolytes

Question 9

When are Signs & Symptoms of HypoPhosphotemia seen?

Answer 9

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

Question 10

S/Sx of HypoPhosphotemia

Answer 10

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

Question 11

Treatment Goals
HypoPhosphotemia

Answer 11

• *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

Question 12

Asymptomatic & 1.5-2mg Phos

ORAL TREATMENT

Answer 12

DIETARY SUPPLEMENTATION
of Phos-Rich Foods
(beer/ale / DARK COLA / cheese / liver / chocolate)

1mmol / kg
(Max 80mmol)
if reduced GFR:
1/2 suggested dose

Question 13

Asymptomatic & 1.0-1.5 mg/dL

Answer 13

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

Question 14

K-Phos Neutral
Phospha 250 Neutral

Oral Phos Supplements

Answer 14

NEED TO KEEP AN EYE ON POTASSIUM

1.1 mEq of K

All have 250 mg Phos = 8 mmol P

Tablet & Packet

Question 15

Phos-Na-K Powder

Oral Phos Supplements

Answer 15

NEED TO KEEP AN EYE ON POTASSIUM

7.2 mEq of K

All have 250 mg Phos = 8 mmol P

PACKET ONLY

Question 16

Neutra-Phos tablet

Oral Phos Supplements

Answer 16

NEED TO KEEP AN EYE ON POTASSIUM

7 mEq of K

All have 250 mg Phos = 8 mmol P

TAB ONLY

Question 17

PHOS-RICH FOODS

Answer 17

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

Question 18

Oral Phosphorous Supplemnts

MONITORING // ADR

Answer 18

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

Question 19

Indication for
INTRAVENOUS PHOS TREATMENT

Answer 19

SYMPTOMATIC HypoPhosphatemia = < 1mg/dl
or
UNABLE to tolerate PO therapies

VVVVV
Switch to ORAL when Phos > 1.5 mg/dl

Question 20

TREATMENT
for A/Symptomatic w/ Phos >1.2

Answer 20

Dietary Supplementation of Phos-Rich Foods

• *0.08 - 0.24** mmol/kg
• *over 6 hours**

(max 30mmol)

Question 21

TREATMENT
for SYMPTOMATIC
w/ Phos <1.2 mg/dL

Answer 21

Dietary Supplementation of Phos-Rich Foods

• *0.25-0.5** mmol/kg
• *over 8-12 hours**

MAX 80 mmol

Question 22

DOSE ADJUSTMENTS for HIGHER DOSES
HypoPhosphatemia

Answer 22

Acute on Chronic

Chronic > 1 week

Question 23

DOSE ADJUSTMENTS for Lower doses
HypoPhosphatemia

Answer 23

Ca 10.5-12 –> 50% of dose

Ca >12 mg/dL –> HOLD PHOS
calcifications can occur –> CORRECT CALCIUM FIRST
renal dysfuncions

Question 24

IV PHOS SUPPLEMENTS

Answer 24

• *SODIUM PHOSPHATE**
• *PREFFERED**, unless also treating K <3.5 mEq/l

Potassium Phosphate
for treating K<3.5

Question 25

Monitoring for
IV PHOS SUPPLEMENTS

Answer 25

Serum Phos = q6hours

Anticipate a drop in Phos 2 days AFTER

Serum:
Calcium / Magnesium / Na-K

Kidney Function
avoid/reduce dose in renal impariment

Question 26

ADR
IV PHOS SUPPLEMENTS

Answer 26

Calcium Phosphorous PRECIPITATION in IVPB
deposit in KIDNEY –> RENAL FAILURE

Complications with:
OVER TREATMENT & INCREASED RATE of ADMIN:
Hypocalcemic tetany
EKG changes
HYPERphos / hypoMAG

Question 27

Treatment in URNARY PHOSPHATE WASTING

Answer 27

difficult to treat

Admin of PHOS –> MORE PHOS EXCRETION

???Dipyridamole???
need more studies, 75mg PO QID