Dietary Management In Glycogen Storage Disorders

Metabolic Integration and Disorders (CHS 344)

Glycogen Storage Disease (GSD)

GSD as a group reflect an inability to GSD as a group reflect an inability to metabolize glycogen to glucose in metabolize glycogen to glucose in the liver. the liver.

It mainly occurs because of a It mainly occurs because of a number of enzymatic defects along number of enzymatic defects along the pathwaythe pathway

There are eleven distinct types of There are eleven distinct types of diseases that are commonly diseases that are commonly considered to be glycogen storage considered to be glycogen storage diseases and all of them are caused diseases and all of them are caused as a result of enzymatic defect in as a result of enzymatic defect in the pathway including type I and III.the pathway including type I and III.

GSD Type I and III GSD type I a also called as von Gierk’s Disease is GSD type I a also called as von Gierk’s Disease is

caused by a defect in the enzyme glucose 1,6 caused by a defect in the enzyme glucose 1,6 phosphatase which impairs gluconeogenesis and phosphatase which impairs gluconeogenesis and glycogenolysisglycogenolysis

Therefore the patient is not able to metabolize Therefore the patient is not able to metabolize glycogen stored in the liver and thus also may suffer glycogen stored in the liver and thus also may suffer from hypoglycemia causing irreparable damage.from hypoglycemia causing irreparable damage.

GSD type I b results from a defect in the enzyme GSD type I b results from a defect in the enzyme glucose 6 phosphate translocase, effecting the glucose 6 phosphate translocase, effecting the transfer of glucose 6 phosphate into endoplasmic transfer of glucose 6 phosphate into endoplasmic reticulum.reticulum.

GSD type III also referred to as Forbe’s or GSD type III also referred to as Forbe’s or debrancher enzyme defect occurs due to deficiency debrancher enzyme defect occurs due to deficiency of amylo-1-6-glucosidase enzyme that prevents of amylo-1-6-glucosidase enzyme that prevents glycogen breakdown beyond branch points.glycogen breakdown beyond branch points.

Symptoms of type I and III

Poor physical growthPoor physical growth HypoglycemiaHypoglycemia HepatomegalyHepatomegaly Abnormal biochemical parameters Abnormal biochemical parameters

especially for cholesterol and especially for cholesterol and triglyceridestriglycerides

Purpose of Dietary Management in GSD

The therapeutic objective of The therapeutic objective of dietary management for GSD is to dietary management for GSD is to provide a constant source of provide a constant source of exogenous glucose to maintain exogenous glucose to maintain plasma glucose in a safe range plasma glucose in a safe range and to avoid hypoglycemia.and to avoid hypoglycemia.

Description and Precautions

Prolonged fasting of <5 to 7 hours must be avoidedProlonged fasting of <5 to 7 hours must be avoided Some patients cannot even tolerate fasting for >3.5 Some patients cannot even tolerate fasting for >3.5

hourshours Normal blood glucose concentration (70-120mg/dl) (2 Normal blood glucose concentration (70-120mg/dl) (2

hours postprandial) must be maintained through out hours postprandial) must be maintained through out the day and night to ameliorate biochemical the day and night to ameliorate biochemical abnormalities.abnormalities.

Consumption of sucrose, fructose, lactose and Consumption of sucrose, fructose, lactose and galactose must be avoided or limitedgalactose must be avoided or limited

Therapy with raw cornstarch administered at regular Therapy with raw cornstarch administered at regular intervals and a high carbohydrate, low fat diet is intervals and a high carbohydrate, low fat diet is advocated to prevent hypoglycemia, the primary goal advocated to prevent hypoglycemia, the primary goal of treatment.of treatment.

Prevention of GSD in infants and children

Young infants may require administration of Young infants may require administration of pancreatic enzyme before ingesting uncooked pancreatic enzyme before ingesting uncooked cornstarch to increase its effectiveness ( Gold cornstarch to increase its effectiveness ( Gold berg and Slonin, 1993)berg and Slonin, 1993)

Some infants and children do very well with oral Some infants and children do very well with oral cornstarch administration while others require cornstarch administration while others require the administration of glucose polymers via the administration of glucose polymers via continuous drip gastric feedings as the means of continuous drip gastric feedings as the means of effectively preventing hypoglycemia episodes effectively preventing hypoglycemia episodes during the night (Wolfsdorf et al, 1990). during the night (Wolfsdorf et al, 1990).

The dose of cornstarch is individualized as 1.75 to The dose of cornstarch is individualized as 1.75 to 2.5gm/kg at 4-6 hour intervals (Chen et al, 1984)and 2.5gm/kg at 4-6 hour intervals (Chen et al, 1984)and have been proved effective. Glucose vehicle used have been proved effective. Glucose vehicle used should be made of lactose free formulashould be made of lactose free formula

Adequacy GSD diet can be adequate if it provides nutrients GSD diet can be adequate if it provides nutrients

in prescribed amounts and if patients consumes in prescribed amounts and if patients consumes all formula and diet(Table 1)all formula and diet(Table 1)

Procedure for nutrition support

Establish PrescriptionEstablish Prescription: Present weight, patients age : Present weight, patients age and patients accurate diet history are important and patients accurate diet history are important requisites for determining nutrient prescription. GSD requisites for determining nutrient prescription. GSD table 1 provides nutrient guides to the clinicians.table 1 provides nutrient guides to the clinicians.

HOW TO FILL DIET PRESCRIPTIONHOW TO FILL DIET PRESCRIPTION Use table 2 for foods allowed and restricted in GSD type Use table 2 for foods allowed and restricted in GSD type

I. Calculate amount of nutrients, fat, protein and CH2O I. Calculate amount of nutrients, fat, protein and CH2O from table 1 that’s required to fill the prescription. If from table 1 that’s required to fill the prescription. If necessary measured amounts of fats, oils or solid foods necessary measured amounts of fats, oils or solid foods can be used to provide prescribed fats; proteins can be can be used to provide prescribed fats; proteins can be supplied with ProVimin( Protein-Vitamin-Mineral formula) supplied with ProVimin( Protein-Vitamin-Mineral formula) or ProMod(Protein supplement; carbohydrate or ProMod(Protein supplement; carbohydrate prescription can be filled by polycose and complex prescription can be filled by polycose and complex carbohydrates or cornstarch.carbohydrates or cornstarch.

See table 3 and 4 for carbohydrates and energy content See table 3 and 4 for carbohydrates and energy content of complex carbohydrates.of complex carbohydrates.

Evaluate safety and adequacy of Planned

nutrition Support Natural foods and appropriate formula should provide enough Natural foods and appropriate formula should provide enough

calories and protein. Supplementation of vitamins and calories and protein. Supplementation of vitamins and minerals is necessary if recommended dietary intake is minerals is necessary if recommended dietary intake is <100% <100%

Iron supplementation is required to maintain adequate Iron supplementation is required to maintain adequate hematologic status as cornstarch interferes with iron hematologic status as cornstarch interferes with iron absorption.absorption.

Osmolality of formulaOsmolality of formula For neonates: < 450mosm/kgH2OFor neonates: < 450mosm/kgH2O For children: < 750mosm/kgH20For children: < 750mosm/kgH20 Adults: < 1000mosm/kgH20Adults: < 1000mosm/kgH20 If osmolality equal to or greater than above mentioned If osmolality equal to or greater than above mentioned

parameters that is more than tolerated by patients increase parameters that is more than tolerated by patients increase water contentwater content

Renal solute load for infants: 1100mosm/kg H20Renal solute load for infants: 1100mosm/kg H20 If renal solute load is greater than renal concentrating ability If renal solute load is greater than renal concentrating ability

of patients, it will result in dehydration.of patients, it will result in dehydration.

Sample diet calculation for GSD

Nutrient Prescription: See GSD table 1Nutrient Prescription: See GSD table 1 For eg: Subject is a female, 5 months old and weighs 4 kgs. For eg: Subject is a female, 5 months old and weighs 4 kgs. TOTAL ENERGY CALCULATIONTOTAL ENERGY CALCULATION Energy requirement for 5 months old patients is app.145 Energy requirement for 5 months old patients is app.145

Kcal / kg(see table 1)Kcal / kg(see table 1) Therefore energy requirement for patient weighing 4 Kgs Therefore energy requirement for patient weighing 4 Kgs

will be =145kcal/kg x 4= 580kcal.will be =145kcal/kg x 4= 580kcal. FATS FATS : out of 580kcal 30% of energy must be provided by : out of 580kcal 30% of energy must be provided by

FatsFats Therefore, 30% of 580 = 30/100x580=174kcal.Therefore, 30% of 580 = 30/100x580=174kcal. Out of 580kcal 174kcal must be provided by fats in the dietOut of 580kcal 174kcal must be provided by fats in the diet We know that 1 gm fats provides with 9kcal of energy We know that 1 gm fats provides with 9kcal of energy

therefore 174kcal÷9kcal of fat per gram= 19gm/d of fat will therefore 174kcal÷9kcal of fat per gram= 19gm/d of fat will provide with 174kcal of energy to GSD patients.provide with 174kcal of energy to GSD patients.

Sample diet calculation for GSD (Cont…)

ProteinsProteins(refer table 1): 10% of total energy required by (refer table 1): 10% of total energy required by GSD patients must be provided by proteins in the diet.GSD patients must be provided by proteins in the diet.

Therefore, 10%of 580kcal=10/100 x 580kcal=58kcalTherefore, 10%of 580kcal=10/100 x 580kcal=58kcal We know that 1gm proteins provides 4kcal of energyWe know that 1gm proteins provides 4kcal of energy Therefore, 58kcal of energy will be provided by Therefore, 58kcal of energy will be provided by

58kcal÷4kcal per gram protein= 14.5gm/d of proteins.58kcal÷4kcal per gram protein= 14.5gm/d of proteins. CarbohydratesCarbohydrates: 60% of total energy required by GSD : 60% of total energy required by GSD

patients must be provided by carbohydrates in the diet.patients must be provided by carbohydrates in the diet. Therefore, 60%of 580kcal=60/100x580kcal=348kcalTherefore, 60%of 580kcal=60/100x580kcal=348kcal We know that 1gm of carbohydrates provides 4kcal of We know that 1gm of carbohydrates provides 4kcal of

energyenergy Therefore, 348kcal of energy will be provided by Therefore, 348kcal of energy will be provided by

348kcal÷4kcal per gram of carbohydrates= 87gm/d of 348kcal÷4kcal per gram of carbohydrates= 87gm/d of carbohydrates.carbohydrates.

How to fill prescription for GSD patients

We now know that total amount of energy required by We now know that total amount of energy required by GSD patients is 580 KcalGSD patients is 580 Kcal

Fats must provide 30% of energy which is equal to Fats must provide 30% of energy which is equal to 174kcal that is 19gms of fats must be consumed by 174kcal that is 19gms of fats must be consumed by GSD patientsGSD patients

Proteins must provide with 10%of energy which is Proteins must provide with 10%of energy which is equal to 58kcal that is 13gms of proteins must be equal to 58kcal that is 13gms of proteins must be consumed by GSD patientsconsumed by GSD patients

Carbohydrates must provide with 60% of energy which Carbohydrates must provide with 60% of energy which is equal to 348kcal that is 87 gms of carbohydrates is equal to 348kcal that is 87 gms of carbohydrates must be consumed by GSD patientsmust be consumed by GSD patients

Therefore, keeping this in mind we can design the Therefore, keeping this in mind we can design the prescription for GSD patientsprescription for GSD patients

PrescriptionMedical Food

Amount Fat(g) Protein(g)

Carbohydrates(g)

Energy(Kcal)

Pregestimil 104gm 19 13 64 473

Cornstarch 12.8gm 12 48

Polycose 15.5gm 15 59

Total 19 13 91 580