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Indian Pediatr 2015;52: 533 |
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Macroamylasemia: A Benign Cause for High
Serum Amylase
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*Jaya Agarwal and #G
Deepika
Departments of Gastroenterology and #Biochemistry,
Asian Institute of Gastroenterology, Hyderabad, Telangana, India.
Email:
[email protected]
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Hyperamylasemia is the most common biochemical marker for the diagnosis
of acute pancreatitis, but has low specificity. A 9-year-old girl
presented to our hospital with complaints of pain abdomen, fever and
vomiting for a week. Her serum amylase done elsewhere was 3500 U/L, and
with suspicion for acute pancreatitis, she was referred to our center.
On examination, her abdomen was soft with mild tenderness in right iliac
area. Her blood investigations indicated a neutrophilia (white blood
cell count 13 × 10 9/L), high
serum amylase (4310 U/L), normal serum lipase (32 U/L), and normal serum
creatinine. Ultrasonography of abdomen showed mild peri-appendicular
edema and normal pancreas. In view of above findings and non-fulfillment
of diagnostic criteria for acute pancreatitis [1], patient was managed
conservatively as a case of acute appendicitis. At follow-up after 4
weeks, she was asymptomatic, but her serum amylase continued to be
abnormally high (2588 U/L), with normal lipase. Ultrasound and
contrast-enhanced computed tomography of abdomen were normal. With no
obvious intrabdominal or salivary pathology to explain such high amylase
values in absence of renal failure, possibility of macroamylasemia was
considered. Amylase creatinine clearance ratio (ACCR) [(urine
amylase/serum amylase) × (serum creatinine/urine creatinine)×100]
estimation was done which was 0.36 (normal 1-4%), confirming the
diagnosis of macroamylasemia.
Apart from pancreatitis, serum amylase is increased
in intestinal obstruction, perforated peptic ulcer, biliary tract
disease, tubo-ovarian pathology, diabetic ketoacidosis, salivary gland
lesions, and renal failure. Macroamylasemia, a rare but benign
condition, results due to circulating macroamylase complexes, which
cannot be cleared by the renal glomeruli. Amylase aggregation with
immunoglobulins, usually IgA (92%), increases their mass to 10 5
Daltons, and thus these macromolecules are not filtered [2]. In the
absence of renal failure, a low ACCR is diagnostic of macroamylasemia
[3]. In acute pancreatitis, amylase clearance increases significantly,
and thus ACCR is increased.
In adults, macroamylasemia is reported in 2.5% of all
hyperamylasemic patients. However, it is rarely reported in children.
There are few pediatric case reports of macroamylasemia with Celiac
disease and Crohn’s disease [4,5].
Failure to immediately identify macroamylasemia as
the cause for persistent hyperamylasemia can lead to extensive
investigations and confusion; hence, early suspicion and identification
is crucial to eliminate diagnostic perplexity.
References
1. Morinville VD1, Husain SZ, Bai H, Barth B, Alhosh
R, Durie PR, et al. Definitions of pediatric pancreatitis and
survey of present clinical practices. J Pediatr Gastroenterol Nutr.
2012;55:261-5.
2. Berk JE, Kizu H, Take S, Fridhandler L.
Macroamylasemia: Clinical and laboratory features. Am J Gastroenterol.
1970;53:211-22.
3. Levine RI, Gleuser FL, Berk JE. Enhancement of the
amylase-creatinine clearance ratio in disorders other than acute
pancreatitis. N Engl J Med. 1975;292:329-32.
4. Barera G, Bazzigaluppi E, Viscardi M, Renzetti F,
Bianchi C, Chiumello G, et al. Macroamylasemia attributable to
gluten-related amylase autoantibodies: A case report. Pediatrics.
2001;107:e93.
5. Venkataraman D, Howarth L, Beattie RM, Afzal NA. A
very high amylase can be benign in pediatric Crohn’s disease. BMJ Case
Rep. 2012:2012.
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