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Tuesday, January 02, 2007

Fatigue & Excessive Thirst

Dear Lisa,

I have a 5 year old son who often complains that he is tired. He gets 10-11 hours of sleep a night on a regular basis, takes vitamins, and eats a fair amount of fruits and vegetables. He seems, however, to drink an extraordinary amount for his age, about 64 oz. or so a day of liquid, with as little sugar as possible. He also craves sugar and salt, consistently asking for candy over toys and other rewards, and sneaking the salt shaker to eat it straight from his hand. He has regular doctor visits, and all his tests come back normal, but I wonder if there isn't something we're missing? Any idea if there is something else we should be concerned about?

“Mom of 3”

Dear “Mom of 3”,

Repeated complaints of Fatigue or complaints of being tired in a five year old can occur due to a multitude of reasons. The most common causes are an electrolyte imbalance, thyroid disorder, anemia, insufficient amount of sleep or a metabolic disease.(1) Since your son is receiving the required amount of sleep, which is 11 hours per night for a five year old child, insufficient sleep should not be an issue in his case.(1)

Lack of nutrition should also not be a factor since your son takes vitamins and eats fruits and vegetables on a regular basis. Anemia may be a concern since you did not mention that your son eats iron fortified foods such as beans, meat or iron-fortified cereals. The most common cause of Anemia in childhood is Iron Deficiency Anemia which is caused by the insufficient dietary intake of iron. The symptoms include pale appearance, irritability, short attention span, poor scholastic performance, pica and fatigue, but some children do not experience any symptoms at all.(1,2) Iron deficiency anemia is diagnosed from a complete blood cell count.

An electrolyte imbalance is another potential cause of Fatigue. Electrolytes such as salt, sugar and potassium need to be in balance in order for the bodily functions to work properly. Our bodies tend to crave things that they need. Therefore an electrolyte imbalance would be suspected in a child who craves salt and/or sugar. One of the most common causes of fluid and electrolyte imbalance in the pediatric population is vomiting and diarrhea due to a stomach virus. Other causes include fever, injuries such as burns, excess sweating and diet.

The body has normal defense mechanisms which attempt to maintain a balance of electrolytes in the body. Infants and young children are more vulnerable towards rapid changes in fluid and electrolyte balance because their regulatory mechanisms are immature.(3) The constant attempts to regulate such imbalances could place a strain on the body and results in symptoms of Fatigue.

Water intoxication can occur when a child drinks too much water. The intake of excessive amounts of water can cause an electrolyte imbalance and a deficit in the amount of sodium in the blood. The symptoms of water intoxication include restlessness, nausea, vomiting, diarrhea, seizures, excessive urination and excessive drinking.(3)

Children at risk for developing water intoxication include infants who are fed formula that is not mixed properly and too much water is added to the mixture, older children who drink fluids that are intentionally diluted with water and children who receive tap water enemas.(4) Water intoxication and the resulting Hyponatremia that develops can cause a person to crave salt which contains sodium. The symptoms of Hyponatremia or insufficient amount of sodium in the blood include lethargy, anorexia, agitation, disorientation, muscles cramps, decreased deep tendon reflexes and seizures.(4)

Besides your son’s complaint of fatigue, the excessive amounts of fluids that he takes is an issue that should be investigated. You reported that he receives about 64 ounces of fluid per day with as little sugar as possible. It would be important to know if the liquid that he is drinking is diluted with water. If the large amount of fluid that your son has been drinking is water or watered down juice, a fluid and electrolyte imbalance may need to be considered. If this is the case it would be a good idea to discuss this with your Doctor and make changes in his diet so that he does not receive more water than he needs.

There are medical conditions that cause a child to have excess thirst or drink a lot. These conditions include Diabetes mellitus, Diabetes Insipidus, abnormal Antidiuretic Hormone (ADH) production and Syndrome of Inappropriate Antidiuretic Hormone. The Antidiuretic hormone (ADH) controls the body’s excretion of water. This hormone is produced by the hypothalamus which is a part of the brain. This hormone causes the kidneys to concentrate urine and balance water and electrolytes. When there is an imbalance in the ADH a child may have too much or too little fluids in their body and a resulting electrolyte imbalance.

A disorder in the production of ADH can occur due to a variety of disorders including Pneumonia, Asthma, Cystic Fibrosis, side effects of medication and Renal tubular acidosis. This does not seem to be the case with your child because you did not mention that he was suffering from any of these conditions. Typically children with these disorders are quite ill.

Diabetes Insipidus is a condition that occurs when the there is a deficiency in the ADH secretion. This deficiency in ADH leads to excess urination, the inability to concentrate urine and conserve body water. As a result a child urinates excessively, urinates at night, and is excessively thirsty. The urine output of a child with Diabetes Insipidus can be between 4 and 10 liters per day.(3)

The symptoms of Diabetes Insipidus are so excessive that they often interfere with the child’s play and sleep. If the child does not get the water that they crave they become irritable. Children with Diabetes Insipidus also experience poor weight gain, growth failure and high levels of sodium in the child’s blood. Diabetes Insipidus is often associated with an underlying disorder.

Diabetes Mellitus is another disorder that causes a child to become dehydrated and have symptoms of excess urination and excess thirst. Diabetes Mellitus is the type of Diabetes that the general public refers to when they are talking about “Diabetes”. Diabetes Mellitus is the inability of the body to properly metabolize sugar, carbohydrates, protein and fat. It is caused by an insulin deficiency which leads to high blood glucose levels.

The symptoms of Diabetes Mellitus include increased fluid intake, increased food intake, increased urination, nausea, vomiting, abdominal pain, weight loss, dehydration, fruity odor on the breath, blurred vision, disorientation and vaginal yeast infections.(4,5) The screening test for Diabetes checks the level of glucose in the blood after a patient has been fasting for eight hours.(6)

There are two types of Diabetes Mellitus, Type 1 and Type 2. Type 1 Diabetes is the type most frequently found in childhood and is caused by a deficiency of insulin secretion. Type 2 Diabetes is associated with insulin resistance and an insufficiency of insulin. There has been an increased incidence of Type 2 Diabetes in children which previously has been considered an adult disease.

This increased frequency of Type 2 Diabetes in children has been linked to the increase in childhood obesity. (6) The symptoms of Type 1 and Type 2 Diabetes are the same, but investigators announced at the American Diabetes Associations recent scientific meeting in Washington, D.C. that new data shows that 2/3 of type 2 Diabetic patients report having no more than one symptom. Most commonly the symptoms reported were frequent urination and fatigue.(5)

Since you reported that your child has had repeat physical examinations and testing, chances are Diabetes and ADH imbalance have already been ruled out. Your Doctor is the best person to speak to regarding the findings of your son’s physical examination and test results. At this point it would be a good idea to keep a 72 hour food diary, recording everything that your child eats and drinks and bring this record to your Physician’s office. Your child’s Doctor will be able to tell you if your child is receiving the correct amount of calories and water for his age and size.

If it is determined that your child is not receiving enough calories for his size, this may be an explanation why he is drinking so much. If he is consuming the correct amount calories and water then continued symptoms of fatigue should be addressed at a follow up appointment with your Doctor.

Acute or sudden onset of Fatigue or weakness in a child can be a sign of a serious or even life threatening condition and needs to be evaluated by a physician without delay. Sudden onset of Fatigue or weakness can be caused by an infection, viral myositis, Transverse myelitis, Guillain-Barre’ Syndrome, Epidural Abscess, Poliomyelitis, Botulism, Tick paralysis or trauma. (1) These conditions can result in serious consequences that can be worsened by a delay in treatment.

For Information about topics discussed read other Pediatric Advice stories:


Vomiting and Dehydration


Iron Requirements for Children

(1) Schwartz M, Charney E, Curry T, Ludwig S. Pediatric Primary Care. A Problem Oriented Approach. 2nd Ed. Littleton, Mass:Year Book Medical Publishers, Inc. 1990: 347-349, 69-70,440-441.
(2)Graham M, Uphold C. Clinical Guidelines in Child Health. Gainsville, Florida: Barmarrae Books. 1994:617.
(3)Betz C, Hunsberger M, Wright S. Family-Centered Nursing Care of Children. 2nd ed. Philadelphia, PA:W.B.Saunders Company. 1994:554,1949-1950.
(4)Behrman R, Kliegman R. Nelson Essentials of Pediatrics. Philadelphia ,PA: W.B.Saunders Company. 1990:556,917,610.
(5)Newsline. Diabetes symptoms often absent, study finds. The Clinical Advisor. 2006. August:14.
(6 )Ho J, Pacaud D, Leung A. Type 2 Diabetes Mellitus in children: A New Challenge for Diagnosis and Prevention. Consultant for Pediatricians. 2006. Feb:77-89.

Lisa-ann Kelly R.N., P.N.P.,C.
Certified Pediatric Nurse Practitioner

Pediatric Advice For Sick Children