26: 9-week-old male not gaining weight

Question 1

Weight Gain in the Newborn

Answer 1

• -Immediately after birth, most newborn infants lose some weight, but it uncommonly exceeds 10% of birth weight.
• -Healthy infants born at full term will gain an average of 20-30 grams per day during the first 4 months of life. Weight doubles by approximately 4 months for the average infant, although some infants reach this weight by 3 months.
• -About half of the weight gained during the first 4 months of life is in the form of fat, making the 4-month-old infant the fattest healthy human, with about 25-26% of weight as fat.
• -Formula-fed infants tend to gain weight faster than do breastfed infants because they ingest more calories.

Question 2

Failure to Thrive (FTT)

Answer 2

• -Weight falls below the 3rd percentile
• -Weight for height/length falls below the 3rd percentile
• -The rate of weight gain slows compared with previous growth, crossing two or more major percentiles on the growth chart in a downward direction.

Question 3

Many conditions can result in FTT, including:

Answer 3

• Chronic diarrhea or vomiting
• Congestive heart failure (CHF)
• Formula allergy
• Improperly prepared formula
• Inadequate formula volume
• Malabsorption
• Parental neglect
• Severe gastroesophageal reflux

Question 4

Organic vs. Non-organic FTT

Answer 4

FTT is categorized as “organic” (meaning the poor growth is secondary to another underlying medical condition) or “non-organic” (meaning there is no identified underlying medical cause). Nearly 90% of cases of FTT in children are non-organic and often relate to issues such as lack of proper feeding or lack of access to adequate food.

Question 5

Normal RBC Values in Infants

Answer 5

• -The mean value for hemoglobin for healthy full-term 2-month-old infants is 11.2 g/dL (112 g/L), an anticipated drop from the mean hemoglobin at birth of 16.5 g/dL (165 g/L).
• -The decrease in hemoglobin occurs because fetal RBCs have a short half-life that leads to a “physiological nadir” for hemoglobin, sometimes also called “physiological anemia.”
• -In full-term newborns the marrow is stimulated to produce new RBCs only when the hemoglobin reaches its nadir of about 11 g/dL (110 g/L) at 7-9 weeks of age, after which the hemoglobin rises.

Question 6

There are many causes of anemia in infants, among them:

Answer 6

• Iron deficiency (causes a microcytic anemia)
• Chronic disease (can cause a normocytic, normochromic anemia)
• Hemolysis (causes a drop in the total number of red blood cells and damages the remaining RBCs)
• Blood loss (causes a normocytic, normochromic anemia)

Question 7

Inheritance Pattern of CF

Answer 7

For an infant to have the disease, both parents must be heterozygote carriers of the mutant allele. Each child of this couple have will have a 25% chance of having CF, a 25% chance of being unaffected, and a 50% chance of being a carrier like his parents.

Question 8

CF Treatment is multi-pronged and includes

Answer 8

• -Nutritional management, with enzymes and vitamins and extra calories
• -Airway clearance, and
• -Treatment of airway infections.

Question 9

General Guidelines for the Diagnostic Evaluation of FTT

Answer 9

• BUN, CR
• CXR
• CBC AND SMEAR
• ELECTROLYTES (SERUM)
• FECAL FAT ANALYSIS
• LFT
• neonatal screen
• occult blood, stool
• O&P, stool
• stool culture
• sweat chloride (sensitivity of 99%, and specificity near 90%.)
• thyroid function tests
• UA
• Urine culture

Question 10

Differential Diagnosis for Failure to Thrive

Answer 10

• CHF
• formula allergy
• gastroenteritis
• hypothyroidism
• malabsorption