Etiology

renal insufficiency

hemodialysis

antacids

acidosis

hypoparathyroidism

catabolism

vitamin D metabolites

mont reid p.26

Complications

may produce metastatic calcification

mnont reid p.26

Treatment

- restrict external sources

- phosphate-binding antacid (Amphogel, ALternaGel)

mont reid p.26

Hypophosphatemia: Differential Diagnosis

- Most commonly seen in chronic alcoholism, DKA, use of phosphate binders, or hyperalimentatiion.

- Hyperalimentation

- recovery from severe thermal injury

- hypothyroidism

- vitamin D deficiency

- alkalosis

- pregnancy

- nutritional recovery after starvation

- diabetic ketoacidosis

- malabsorption

- phosphate-binding antacids

- alcoholism

- acute tubular necrosis

- prolonged alkalosis

- hemodialysis

- starvation

- Decreased intake:

  - malnutrition

  - malabsorption

  - vitamin D deficiency

  - phosphate binders

  - alcoholism

- Shifts from serum into cells:

  - alkalosi

  - hyperalimentation

  - effects of insulin/glucagon/androgens

  - hungry bone syndrome

  - sepsis

  - refeeding syndrome

-refeeding syndrome refers to the entity of metabolic and electrolyte abnormalities (most notably hypophosphatemia) that occur in high risk malnourished patients (alcohoilc, anorexic, chronic diarrhea/vomiting), 24-72 hours after initiating nutrition.)

- Important to be vigilant of this possibility in  at-risk patients, monitor for electrolytes/vitamin deficiencies, and initiate caloric intake with care.

- Increased urinary secretion:

  - renal tubular defect

  - DKA

  - hyperparathyroidism

  - Vitamin D deficiency

source

HH new p.151

mont reid p.25

Hypophosphatemia: History and Physical Exam

- Physical signs are generally seen only with total blody depletion and serum P < 1mg/dL

- anorexia, bone pain, weakness, CNS changes, hemolysis, platelet and granulocyte dysfunction, cardiac arrest

- weakness

- rhabdomyolysis

- respiratory compromise/failure

- CHF (impaired cardiac contractility)

- ileus

- hematologic dysfunction

- paresthesias

- confusion

- stumor

- seizures

- coma

source

HH new p.151

mont reid p.25

Hypophosphatemia: Treatment

Parenteral

- IV NaPO4 or KPO4 if unable to take PO or if severe

- recent onset: 0.08-0.2 mmol/kg over 6 hours

- prolonged: 0.16-0.24 mmol/kg over 6 hours

Enteral

- Neutra-Phos - 2 caps BID-TID (250mg phosphorus/tab)

- Phospho-Soda  5mL BID-TID (129mg phosphorus/mL)

mont reid p.26

Hypophosphatemia: Pathophysiology

- myocardial depression secondary to low ATP levels

- shift in oxyhemoglobin curve secondary to decreased 2,3-diphosphoglycerate levels

mont reid p.25

Hypophosphatemia: [Schwartz, p.58]

- Hypophosphatemia can be due to a decrease in phosphorus intake, an intracellular shift of phosphorus, or an increase in phosphorus excretion.

- Decreased GI uptake due to malabsorption or administration of phosphate binders and decreased dietary intake from malnutrition are causes of chronic hypophosphatemia.

- Most acute cases are due to an intracellular shift of phosphorus in association with respiratory alkalosis, insulin therapy, refeeding syndrome, and hungry bone syndrome.

- clinical manifestations of hypophosphatemia usually are absent until levels fall significantly.

- In general, symptoms are related to adverse effects on the oxygen availability of tissue and to a decrease in high-energy phosphates, and can be manifested as cardiac dysfunction or muscle weakness.

Schwartz, p.58

Hypophosphatemia: Treatment [Schartz, p. 62]

Phosphate level 1.0 - 2.5 mg/dL

PO
- Tolerating enteral nutrition: Neutra-Phos 2 packets Q6H per gastric tube or feeding tube

IV

- No enteral nutrition: KPHO4 or NaPHO4 0.15mmol/kg IV over 6h X 1 dose

- Recheck phosphate level in 3d

Phosphate level <1.0 mg/dL
PO

- Tolerating enteral nutrition: KPHO4 or NaPOH4 0.25mmol/kg over 6h X 1 dose

- Recheck phosphate level 4h after end of infusion; if <2.5mg/dL, begin Neutra-Phos 2packets Q6H

IV

- Not tolerating enteral nutrition: KPHO4 or NaPHO4 0.25 mmol/kg (LBW) over 6h X 1 dose

- Recheck phosphate level 4h after end of infusion; if <2.5mg/dL, then KPHO4 or NaPO4 0.15mmol/kg (LBW) IV over 6h X 1 dose

Schwartz, p.62

Hypophosphatemia MCQ [absite question book, p.29, Q61][b]

#61. Which of the following abnormalities can cause prolonged ventilation

a. Hypokalemia

b. hypomagnesemia

c. hyponatremia

d. hypophosphatemia

.

.

.

.

.

- The answer is d.

- Hypophosphatemia can result in prolonged ventilation due to relative ATP insufficiency (need phosphate to convert ADP to ATP)

- K and Mg are important ions involved in gut motility (these should be replaced in patients with a prolonged ileus)

- Deficiencies in K and Mg can also contribute to heart arrhythmias such as atrial fibrillation.

absite question book, p.29, Q61

Phosphate

[phosphate nl 2.7-4.5mg/dL >60 y; M 2.3-3.7; F 2.8-4.1 mg/dL]

Phosphorus

- involved in enzyme regulation, energy storage, oxygen transport, proton buffering, and maintenance of cell wall integrity

- mostly intracellular

- 80% is found in bone

- 80% is absorbed in the duodenum

mont reid p.17

maxwell cards

OBE: SCORE: HYPOPHOSPHATEMIA: 5 MINUTE REVIEW

ORAL BOARDS: 5 MINUTE REVIEW TEMPLATE

EPONYMS

- "  " sign, etc

DEFINITIONS

ANATOMY

NORMAL PHYSIOLOGY

PATHOPHYSIOLOGY

STATISTICS

TYPES

CLASSIFICATION / GRADING

DDX / CAUSES / ETIOLOGY

RISK FACTORS

HISTORY OF PRESENT ILLNESS

PHYSICAL EXAM

RENAL/FLUID STATUS

DIAGNOSIS

WORKUP

MONITORING

COMPLICATIONS OF THE DISEASE

TREATMENT: MEDICAL

TREATMENT: SURGERY: INDICATIONS

 TREATMENT: SITUATIONS

SURGERY OPTION #1

1. PREOPERATIVE MANAGEMENT

2. STEPS

3. POSTOPERATIVE MANAGEMENT

4. COMPLICATIONS

COMPLICATIONS (GENERAL)

MISCELLANEOUS TOPICS