Biochemical features of dietary chloride deficiency syndrome: A comparative study of 30 cases

Biochemical features of dietary chloride deficiency syndrome." A comparative study of 30 cases The diagnosis in one infant o f a severe state o f chloride deficiency after ingesting a diet consisting exclusively o f a modified cow milk formula containing only 0.5 mEq/lO0 kcal chloride ion led to the identification o f 30 additional infants (age 2.6 +__0.7 months)fed the same commercial formula. The total absence o f chloride in the urine was used as a biochemical index o f subclinical dietary chloride deficiency. Serum and urine values were studied at diagnosis and 10 to 12 days after chloride replenishment, and compared statistically with the values obtained in a control group o f 40 infants (age 2.8 +- 1.2 months)fed exclusively a different modified formula containing an adequate chloride concentration. The outstanding laboratory abnormalities noted in the infants ingesting a low chloride formula were hypochloremia and metabolic alkalosis. Mean serum concentrations o f potassium, urea, creatinine, and uric acid were in the normal range, but group values were statistically different from normal. A previously unreported finding was the demonstration o f a significant elevation in the serum concentrations o f calcium and phosphate and in the urinary excretions o f calcium and magnesium, which persisted after almost complete recovery o f the remaining biochemical disturbances. These results indicate the potential risk of nephrocalcinosis after dietary chloride deficiency. (J PEDIATR 103:209, 1983)

Juan Rodriguez-Soriano, M.D., Aifredo Vallo, M.D., Gonzalo Castillo, M.D., Roberto Oliveros, M.D., Jos~ M. Cea, M.D., and M. Jos~ Balzategui, M.D. Bilbao. Spain

DIETARY CHLORIDE DEFICIENCY SYNDROME has been recognized in the United States in a number of infants fed certain chloride-deficient batches of Neo-Mull-Soy (Syntex Laboratories) manufactured in 1978 and 1979 ~-6 but only exceptionally in breast-fed infants. 7 The clinical features of the syndrome (failure to thrive, anorexia, muscular weakness, lethargy, vomiting, and dehydration) are well characterized, but the laboratory features, other than hypochloremic metabolic alkalosis, hypokalemia, and hypochloruria, have not been systematically investigated. In recent years the salt content of commercial formulas has been markedly reduced, and in the spring of 1981 a modified cow milk formula was marketed in Spain with a

From the Division o f Pediatric Nephrology, Department o f Pediatrics, Hospital Infantil de la Seguridad Social and University School o f Medicine. Reprint requests: J. Rodriguez-Soriano, M.D., Hospital Infantil de la Seguridad Social, Cruces, Bilbao, Spain.

chloride content of only 0.5 m E q / 1 0 0 kcal (Aptamil-1, Milupa S,A., Spain). The identification of 30 infants with dietary chloride deficiency has permitted us to examine the full biochemical pattern of the syndrome and to report some abnormalities not previously recognized. CASE REPORT In August 1981 a 4-month-old boy was admitted for evaluation of anorexia, lethargy, and muscular weakness. He was the 4.4 kg product of a normal term pregnancy. He was breast-fed for the first six weeks of life, and thereafter his daily dietary intake consisted exculsively of Aptamil-1; a recently marketed modified cow milk formula, which was labeled to contain 3 mEq/L chloride once reconstituted (in fact, the chloride concentration was only 2 mEq/L when measured in the specific batch; the concentrations of other electrolytes and minerals were sodium 11 mEq/L, potassium 13 mEq/L, calcium 640 mg/L and phosphorus 350 mg/L). Physical examination revealed signs of extracellular dehydration with oliguria. No growth failure was present; weight was 6.6 kg (ninetieth percentile), and length was 67 cm (ninety-seventh percentile). Laboratory findings showed hypochloremic metabolic

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The Journal of Pediatrics August 1983

Table I. Biochemical data in serum of infants with dietary chloride deficiency

Chloride-deficient infants

(1)* pH Pco2 (mm Hg) HCo3 (mEq/L) Na (mEq/L) K (mEq/L) C1 (mEq/L) Osmolarity (mOsm/L) Urea (mg/dl) Creatinine (mg/dl) Uric acid (mg/dl) Ca (mg/dl) PO4 (mg/dl) Mg (rag/all)

7.48 37.8 28.1 140.4 4.3 94.6 280.4 23.3 0.31 6.1 10.7 6.6 2.0

_+ 0.03 +__4.1 _+ 2.8 _+ 1.8 _+ 0.5 + 3.6 +_ 5.7 +_ 6.3 +_ 0.08 _+ 1.4 + 0.7 +_ 0.6 +_ 0.2

]

(2)t 7.40 35.1 21.7 141.4 5.2 103.0

+ 0.04 ___ 3.6 ___ 2.4 _+ 3.0 _+ 0.5 +__2.6 -17.6 _ 7.3 0.23 + 0.05 4.6 ___0.9 10.4 +_ 0.4 6.2 +_ 0.6 1.8 _+ 0.2

P

Normal infants 7.42 34.9 22.5 140.8 5.0 103.8 282.6 17.5 0.23 4.5 9.8 5.9 1.9

(N)

(1 vs 2)

(1 vsN)

(2 vs N)

+ 0.04 +_ 4.6 +_ 1.9 +_ 2.7 _+ 0.5 +_ 3.1 +- 4.1 + 7.8 _+ 0.1 + 1.7 + 0.7 _+ 0.8 +_ 0.2