ROLE OF LAB IN ROLE OF LAB IN COMMON PEDIATRIC COMMON PEDIATRIC

EMERGENCIESEMERGENCIES

BYBYPROF./MOUSTAFA RIZKPROF./MOUSTAFA RIZK

CLINICAL PATHOLOGY D.CLINICAL PATHOLOGY D.ALEXANDRIA UNIVERSITYALEXANDRIA UNIVERSITY

Acute abdomenAcute abdomenApneaApneaAppendicitisAppendicitisBacteremia and SepsisBacteremia and SepsisBronchiolitisBronchiolitisDehydrationDehydrationDiabetic ketoacidosisDiabetic ketoacidosis

Febrile SeizuresFebrile Seizures FeverFever

Foreign Body IngestionForeign Body IngestionGastroenteritisGastroenteritis

Gastrointestinal BleedingGastrointestinal BleedingHeadacheHeadacheHenoch-Schönlein PurpuraHenoch-Schönlein Purpura

HypoglycemiaHypoglycemiaIntussusceptionIntussusception

Meningitis,enchephalitisMeningitis,enchephalitis Otitis Media Otitis Media

Pneumonia Pneumonia Pyloric Stenosis Pyloric Stenosis Respiratory Distress Syndrome Respiratory Distress Syndrome Urinary Tract Infections and Pyelonephritis Urinary Tract Infections and Pyelonephritis

Pediatrics, Diabetic Pediatrics, Diabetic KetoacidosisKetoacidosis

Diabetic ketoacidosis (DKA) is a Diabetic ketoacidosis (DKA) is a complex metabolic state of complex metabolic state of hyperglycemia, ketosis, and hyperglycemia, ketosis, and acidosis. DKA results from acidosis. DKA results from untreated absolute or relative untreated absolute or relative deficiency of insulin in type 1 or deficiency of insulin in type 1 or type 2 diabetes mellitus, type 2 diabetes mellitus, respectivelyrespectively. .

Incidence of type 1 diabetes Incidence of type 1 diabetes mellitus is 2 per 1000. The exact mellitus is 2 per 1000. The exact incidence of DKA is unknown but is incidence of DKA is unknown but is estimated to be 4-8 per 1000estimated to be 4-8 per 1000

Hyperglycemia results from Hyperglycemia results from impaired glucose uptake because impaired glucose uptake because of insulin deficiency and excess of insulin deficiency and excess glucagon with resultant glucagon with resultant gluconeogenesis and gluconeogenesis and glycogenolysisglycogenolysis

Glucagon excess also increases Glucagon excess also increases lipolysis with the formation of lipolysis with the formation of ketoacids. Ketone bodies provide ketoacids. Ketone bodies provide alternative usable energy sources alternative usable energy sources in the absence of intracellular in the absence of intracellular glucoseglucose. .

The ketoacids (acetoacetate, The ketoacids (acetoacetate, beta-hydroxybutyrate, acetone) beta-hydroxybutyrate, acetone) are products of proteolysis and are products of proteolysis and lipolysislipolysis..

Hyperglycemia causes an osmotic Hyperglycemia causes an osmotic diuresis that leads to excessive diuresis that leads to excessive loss of free water and electrolytes. loss of free water and electrolytes. Resultant hypovolemia leads to Resultant hypovolemia leads to tissue hypoperfusion and lactic tissue hypoperfusion and lactic acidosisacidosis. .

Ketosis and lactic acidosis Ketosis and lactic acidosis produce a metabolic acidosisproduce a metabolic acidosis

Electrolyte imbalances are the Electrolyte imbalances are the consequences of consequences of hyperglycemia, hyperosmolality, hyperglycemia, hyperosmolality, and acidosisand acidosis. .

Serum hyperkalemia occurs as Serum hyperkalemia occurs as potassium ions shift from the potassium ions shift from the intracellular to extracellular space intracellular to extracellular space because of acidosis from insulin because of acidosis from insulin deficiency and decreased renal deficiency and decreased renal tubular secretiontubular secretion..

Hyponatremia results from a Hyponatremia results from a dilutional effect as free water dilutional effect as free water shifts extracellularly because of shifts extracellularly because of high serum osmolarityhigh serum osmolarity..

Similar decreases in serum Similar decreases in serum phosphate and magnesium phosphate and magnesium concentrations are the result of concentrations are the result of ion shiftsion shifts. .

As serum osmolarity increases As serum osmolarity increases from hyperglycemia, from hyperglycemia, intracellular osmolality in the intracellular osmolality in the brain also increasesbrain also increases..

With current medical therapy, DKA With current medical therapy, DKA has a 2-5% mortality rate. Mortality has a 2-5% mortality rate. Mortality results from the precipitating results from the precipitating underlying cause, which is primarily underlying cause, which is primarily cerebral edema. Cerebral edema cerebral edema. Cerebral edema occurs in 0.3% to 1.0% of all occurs in 0.3% to 1.0% of all episodes of DKAepisodes of DKA..

CLASSIC SYMPTOMS CLASSIC SYMPTOMS

Nausea/vomitingNausea/vomiting Abdominal painAbdominal pain PolydipsiaPolydipsia PolyuriaPolyuria PolyphagiaPolyphagia Weight lossWeight loss

DIFFERENTIAL DIAGNOSISDIFFERENTIAL DIAGNOSIS

Metabolic Acidosis Metabolic Acidosis Pediatrics, Bacteremia and Sepsis Pediatrics, Bacteremia and Sepsis Pediatrics, Dehydration Pediatrics, Dehydration Pediatrics, Gastroenteritis Pediatrics, Gastroenteritis Pediatrics, Pneumonia Pediatrics, Pneumonia Pediatrics, Pyloric Stenosis Pediatrics, Pyloric Stenosis Toxicity, SalicylateToxicity, Salicylate

LABORATORY STUDIESLABORATORY STUDIES

1-Serum glucose (eg, Accu-Chek, 1-Serum glucose (eg, Accu-Chek, Dextrostix) determination of Dextrostix) determination of hyperglycemia provides the hyperglycemia provides the opportunity for rapid diagnosis and opportunity for rapid diagnosis and treatment of DKA. However, a urine treatment of DKA. However, a urine analysis (dip for sugar and ketones) analysis (dip for sugar and ketones) also is acceptablealso is acceptable..

2-Serum potassium 2-Serum potassium This is the most important electrolyte This is the most important electrolyte

disturbance in patients with severe disturbance in patients with severe DKADKA..

•A patient with a low serum potassium level should be assumed to have a potentially life-threatening total body potassium level.

3-Blood and urine cultures3-Blood and urine cultures 4-Urine osmolality4-Urine osmolality 5-Serum osmolality5-Serum osmolality

6-Arterial blood gas 6-Arterial blood gas Venous blood gases are an alternative Venous blood gases are an alternative

and may be kinder for patients.and may be kinder for patients... A recent adult study of DKA patients A recent adult study of DKA patients

concluded that venous blood gases concluded that venous blood gases accurately demonstrated the degree of accurately demonstrated the degree of acidosisacidosis..

7-Obtain serum sodium, chloride, 7-Obtain serum sodium, chloride, bicarbonate, BUN, creatinine, magnesium, bicarbonate, BUN, creatinine, magnesium, calcium, and phosphate levelscalcium, and phosphate levels..

8-Glycosylated hemoglobin: In a patient with 8-Glycosylated hemoglobin: In a patient with known diabetes, high percentages of known diabetes, high percentages of glycosylated hemoglobin (Hgb A1C) indicate glycosylated hemoglobin (Hgb A1C) indicate poor compliance with insulin therapypoor compliance with insulin therapy..

9-CBC.9-CBC.

10-As acidosis corrects, acetoacetate 10-As acidosis corrects, acetoacetate and acetone levels increase in and acetone levels increase in proportion to beta-hydroxybutyrate. As it proportion to beta-hydroxybutyrate. As it worsens, the reverse occurs. Routine worsens, the reverse occurs. Routine laboratory testing for ketones measures laboratory testing for ketones measures only the presence of acetoacetate and only the presence of acetoacetate and acetone, not beta-hydroxybutyrate. acetone, not beta-hydroxybutyrate. . .

Therefore, ketosis may appear Therefore, ketosis may appear to be absent in early DKA and to to be absent in early DKA and to worsen as severe DKA worsen as severe DKA resolvesresolves. .

2- DEHYDRATION2- DEHYDRATION

The term dehydration commonly is The term dehydration commonly is used to denote intravascular fluid used to denote intravascular fluid depletion. However, it is important depletion. However, it is important to understand that volume to understand that volume depletion is distinct from depletion is distinct from dehydrationdehydration. .

Volume depletion denotes Volume depletion denotes contraction of the total intravascular contraction of the total intravascular plasma pool, while dehydration plasma pool, while dehydration denotes loss of plasma-free water denotes loss of plasma-free water disproportionate to loss of sodium, disproportionate to loss of sodium, the main intravascular solutethe main intravascular solute

Isonatremic volume depletion Isonatremic volume depletion

In children with dehydration, the In children with dehydration, the most common underlying problem most common underlying problem actually is volume depletion, not actually is volume depletion, not dehydration. Intravascular sodium dehydration. Intravascular sodium levels are within the reference levels are within the reference rangerange

Pediatric patients, especially those Pediatric patients, especially those younger than 4 years, tend to be younger than 4 years, tend to be more susceptible to volume more susceptible to volume depletion as a result of vomiting, depletion as a result of vomiting, diarrhea, or increases in insensible diarrhea, or increases in insensible water losseswater losses. .

Hyponatremic volume depletion Hyponatremic volume depletion

This is characterized by plasma This is characterized by plasma volume contraction with free water volume contraction with free water excess. An example is a child with excess. An example is a child with diarrhea who has been given tap diarrhea who has been given tap water to replete diarrheal losses. water to replete diarrheal losses. Free water is replenished, but Free water is replenished, but sodium and other solutes are not.sodium and other solutes are not.

Serum sodium levels less than 120 Serum sodium levels less than 120 mEq/L may result in seizures. If mEq/L may result in seizures. If intravascular free water excess is not intravascular free water excess is not corrected during volume replenishment, corrected during volume replenishment, the shift of free water to the intracellular the shift of free water to the intracellular fluid compartment may cause cerebral fluid compartment may cause cerebral edema.edema.

Hypernatremic volume depletion Hypernatremic volume depletion

This is characterized by plasma This is characterized by plasma volume contraction with volume contraction with disproportionate further free water disproportionate further free water loss. Dehydration, or excess free loss. Dehydration, or excess free water loss, is present when plasma water loss, is present when plasma osmolarity increases.osmolarity increases.

An example is the child with diarrhea An example is the child with diarrhea whose fluid losses have been whose fluid losses have been replenished with hypertonic soup, replenished with hypertonic soup, boiled milk, baking soda, or improperly boiled milk, baking soda, or improperly diluted infant formula. Volume has been diluted infant formula. Volume has been restored, but free water has not.restored, but free water has not.

As in hyponatremia, hypernatremic As in hyponatremia, hypernatremic volume depletion may result in serious volume depletion may result in serious central nervous system (CNS) effects central nervous system (CNS) effects as a result of structural changes in as a result of structural changes in central neurons. However, cerebral central neurons. However, cerebral shrinkage occurs instead of cerebral shrinkage occurs instead of cerebral edema.edema.

Potassium considerations Potassium considerations

Although a potassium deficit is present in Although a potassium deficit is present in all patients with volume depletion, it is not all patients with volume depletion, it is not usually clinically significant. However, usually clinically significant. However, failure to correct for a potassium deficit failure to correct for a potassium deficit during volume repletion may result in during volume repletion may result in clinically significant hypokalemia.clinically significant hypokalemia.

Acid and base problems Acid and base problems

Some degree of metabolic acidosis is common, Some degree of metabolic acidosis is common, especially in infants. especially in infants.

Mechanisms include bicarbonate loss in stool Mechanisms include bicarbonate loss in stool and ketone production. Hypovolemia causes and ketone production. Hypovolemia causes decreased tissue perfusion and increased lactic decreased tissue perfusion and increased lactic acid production. Decreased renal perfusion acid production. Decreased renal perfusion causes decreased glomerular filtration rate, causes decreased glomerular filtration rate, which in turn leads to decreased hydrogen (H+) which in turn leads to decreased hydrogen (H+) ion excretion. These factors combine to produce ion excretion. These factors combine to produce a metabolic acidosis. a metabolic acidosis.

DIFFERENTIAL DIAGNOSISDIFFERENTIAL DIAGNOSIS

Diabetic Ketoacidosis Diabetic Ketoacidosis Hypernatremia Hypernatremia Hyperosmolar Hyperglycemic Nonketotic Coma Hyperosmolar Hyperglycemic Nonketotic Coma Hypokalemia Hypokalemia Hyponatremia Hyponatremia Metabolic Acidosis Metabolic Acidosis Pediatrics, Pyloric Stenosis Pediatrics, Pyloric Stenosis Shock, Hypovolemic Shock, Hypovolemic

LABORATORY STUDIESLABORATORY STUDIES

Serum electrolytes are important to determine Serum electrolytes are important to determine sodium concentration.sodium concentration.

Bicarbonate and potassium levels also are Bicarbonate and potassium levels also are important to assess the degree of metabolic important to assess the degree of metabolic acidosis and to screen for coexisting acidosis and to screen for coexisting hypokalemia.hypokalemia.

Blood urea nitrogen and creatinine measure Blood urea nitrogen and creatinine measure renal function and intravascular volume.renal function and intravascular volume.

Glucose may reveal hyperglycemia or Glucose may reveal hyperglycemia or hypoglycemia.hypoglycemia.

Determination of serum osmolarity .Determination of serum osmolarity .

Arterial blood gases are indicated in patients Arterial blood gases are indicated in patients with severe volume depletion. Serum arterial pH with severe volume depletion. Serum arterial pH provides a more direct measure of acidosis than provides a more direct measure of acidosis than the calculated bicarbonate level.the calculated bicarbonate level.

Urine specific gravity indicates the degree of Urine specific gravity indicates the degree of volume depletion and may reveal an underlying volume depletion and may reveal an underlying infectious etiology.infectious etiology.

Urine electrolytes and osmolarity are useful in Urine electrolytes and osmolarity are useful in severe instances or where extrinsic fluid loss is severe instances or where extrinsic fluid loss is poorly understood.poorly understood.

3-Meningitis and Encephalitis3-Meningitis and Encephalitis

Despite advances in antimicrobial and Despite advances in antimicrobial and general supportive therapies, central general supportive therapies, central nervous system (CNS) infections remain a nervous system (CNS) infections remain a significant cause of morbidity and mortality significant cause of morbidity and mortality in children. in children.

As classical signs and symptoms often are As classical signs and symptoms often are not present, especially in the younger not present, especially in the younger children, diagnosing CNS infections is a children, diagnosing CNS infections is a challenge to the emergency physician.challenge to the emergency physician.

The most common causative organisms in The most common causative organisms in the first month of life are :the first month of life are :

Escherichia coli

B streptococci

Listeria monocytogenes

Neisseria meningitidis

Haemophilus influenzae

In those older than 2 months, In those older than 2 months, S S pneumoniaepneumoniae and and N meningitidisN meningitidis currently currently cause the majority of the cases of cause the majority of the cases of bacterial meningitis.bacterial meningitis.

The bacteremic phase allows penetration The bacteremic phase allows penetration of the cerebrospinal fluid (CSF) through of the cerebrospinal fluid (CSF) through the choroid plexus. the choroid plexus.

The CSF is poorly equipped to control infection because type-specific antibodies do not penetrate the blood brain barrier well and complement components are absent or in low

concentrations.

The cell walls of both gram-positive and The cell walls of both gram-positive and gram-negative bacteria contain potent gram-negative bacteria contain potent triggers of the inflammatory response. triggers of the inflammatory response.

In the gram-positive bacteria, teichoic acid

In gram-negative bacteria, lipopolysaccharide or endotoxin

These components are released in the CSF during bacterial growth and especially with the lysis of bacterial cells. With therapy causes a significant release of the mediators of the

inflammatory response.

The mediators of the inflammatory The mediators of the inflammatory response include :response include :

Cytokines as

tumor necrosis factor

interleukin 1, 6, 8, 10

Platelet activating factor

Nitric oxide

Prostaglandin

Leukotrienes

These mediators cause disruption of These mediators cause disruption of the blood brain barrier, vasodilation, the blood brain barrier, vasodilation, neuronal toxicity, meningeal neuronal toxicity, meningeal inflammation, platelet aggregation, inflammation, platelet aggregation, and activation of leukocytes. and activation of leukocytes.

Viral meningitis is the most common Viral meningitis is the most common infection of the CNS. It most frequently infection of the CNS. It most frequently occurs in children younger than 1 year. occurs in children younger than 1 year. Enterovirus is the most common causative Enterovirus is the most common causative agent and is a frequent cause of febrile agent and is a frequent cause of febrile illnesses in childrenillnesses in children

LABORATORY STUDIESLABORATORY STUDIES

Complete blood count (CBC) with differentialComplete blood count (CBC) with differential Blood culturesBlood cultures Coagulation studiesCoagulation studies Serum glucoseSerum glucose Erythrocyte sedimentation rate (ESR)Erythrocyte sedimentation rate (ESR) ElectrolytesElectrolytes Serum and urine osmolalitiesSerum and urine osmolalities Bacterial antigen studies can be done on urine Bacterial antigen studies can be done on urine

and serum.and serum.

The most important laboratory study is The most important laboratory study is examination of CSF: examination of CSF:

Cell countCell count Gram stainGram stain Culture and sensitivityCulture and sensitivity GlucoseGlucose Protein and antigenProtein and antigen Acid-fast bacillusAcid-fast bacillus Fungal stainsFungal stains

Bacterial meningitisBacterial meningitis White blood cell (WBC) counts over 1000/mmWhite blood cell (WBC) counts over 1000/mm 33

usually are caused by bacterial infections. usually are caused by bacterial infections. Counts of 500-1000/mmCounts of 500-1000/mm33 may be bacterial or may be bacterial or viral and need further evaluation. Lower counts viral and need further evaluation. Lower counts are usually associated with viral infections. It are usually associated with viral infections. It was generally believed that a predominance of was generally believed that a predominance of polymorphonucleocytes (PMNs) pointed to polymorphonucleocytes (PMNs) pointed to bacterial meningitis.bacterial meningitis.

Gram stain may aid in diagnosis. Gram stain may aid in diagnosis.

The protein concentration usually is elevated in The protein concentration usually is elevated in bacterial meningitis, but it also is elevated by a bacterial meningitis, but it also is elevated by a traumatic tap. The glucose is usually reduced in traumatic tap. The glucose is usually reduced in bacterial meningitis. Levels less than 50% of bacterial meningitis. Levels less than 50% of serum are suggestive of bacterial meningitis.serum are suggestive of bacterial meningitis.

Latex agglutination tests are available to test for Latex agglutination tests are available to test for S pneumoniae, H influenzae,S pneumoniae, H influenzae, group B group B Streptococcus,Streptococcus, and and N meningitidisN meningitidis. These are . These are especially useful if the child has received especially useful if the child has received antibiotics.antibiotics.

Even with normal CSF results, the fluid should Even with normal CSF results, the fluid should be sent for culture. be sent for culture. N meningitidisN meningitidis and and S S pneumoniaepneumoniae are known to give normal CSF are known to give normal CSF results.results.

Viral meningitis:Viral meningitis: The WBC count in viral meningitis is The WBC count in viral meningitis is

usually below 500/mmusually below 500/mm33, with greater than , with greater than 50% lymphocytes. 50% lymphocytes.

The protein may be elevated.The protein may be elevated. The glucose level may be normal or low. The glucose level may be normal or low. Gram stain results are negative.Gram stain results are negative.

Traumatic LP:Traumatic LP: If bleeding occurs during the procedure and the If bleeding occurs during the procedure and the

CSF is contaminated with blood, the CSF is contaminated with blood, the interpretation becomes more difficult. interpretation becomes more difficult.

There are several techniques for interpreting the There are several techniques for interpreting the results. One involves comparing the peripheral results. One involves comparing the peripheral WBC and red blood cell (RBC) count to that of WBC and red blood cell (RBC) count to that of the CSF. the CSF.

In any situation when a traumatic LP occurs and In any situation when a traumatic LP occurs and the interpretation is difficult, it is better to treat the interpretation is difficult, it is better to treat and wait for the results of the CSF culture. and wait for the results of the CSF culture.

ACUTE ABDOMENACUTE ABDOMEN

Abdominal pain is one of the most Abdominal pain is one of the most common presentations in the pediatric common presentations in the pediatric emergency department. The most emergency department. The most important concern is to decide if the important concern is to decide if the condition requires surgical intervention or condition requires surgical intervention or can be managed medically.can be managed medically.

Causes of acute abdomenCauses of acute abdomen

In first few years of life –In first few years of life – 1. Congenital abnormalities1. Congenital abnormalities

2. Incarcerated inguinal hernia2. Incarcerated inguinal hernia3. Intussuception3. Intussuception4. Intestinal volvulus4. Intestinal volvulus5. GI perforation5. GI perforation

In older childrenIn older children – – 1.Trauma1.Trauma

2. Pancreatitis2. Pancreatitis3. Meckel’s diverticulum3. Meckel’s diverticulum4. Primary peritonitis4. Primary peritonitis5. Intestinal worm infestation5. Intestinal worm infestation

In adolescents –In adolescents – 1. Acute appendicitis1. Acute appendicitis

2. Cholecystitis (acalculous)2. Cholecystitis (acalculous)3. Testicular torsion3. Testicular torsion4. Rupture of ovarian cyst4. Rupture of ovarian cyst

Non- surgical causes of abdominal pain Non- surgical causes of abdominal pain 1. Hyperthyroidisin1. Hyperthyroidisin

2. Addison’s disease2. Addison’s disease3. Diabetic ketoacidosis3. Diabetic ketoacidosis4. Hypercalcemia4. Hypercalcemia5. Lead poisoning5. Lead poisoning6. Porphyria6. Porphyria

Investigations in a child with acute Investigations in a child with acute abdomenabdomen

•The WBC count is elevated in approximately 70-90% of patients with acute appendicitis but also is elevated in many other abdominal conditions

INCREASED WBC >10,000/cu.mm.

•Because at least 10% of patients with appendicitis have a WBC count within the reference range, appendicitis cannot be excluded based on a WBC count within the reference range. •If the WBC count exceeds 15,000 cells/cumm3, the patient is more likely to have a perforation.

Intussuception : Intussuception : Later increased WBC.Later increased WBC. Malrotation : Malrotation : Increased WBC (late sign).Increased WBC (late sign). Cholecystitis : Increased WBC Cholecystitis : Increased WBC Peripheral smear Peripheral smear for Sickle cell.for Sickle cell.

Urine examinationUrine examination : :Microscopic Microscopic examination can evaluate for presence examination can evaluate for presence of WBCs ( per high-power field), RBCs, of WBCs ( per high-power field), RBCs, bacteria, casts, and skin contamination bacteria, casts, and skin contamination (eg, epithelial cells),this indicate UTI.(eg, epithelial cells),this indicate UTI.

A clean-catch urine sample with more A clean-catch urine sample with more than 100,000 colony-forming units than 100,000 colony-forming units (CFU) of a single organism is classic (CFU) of a single organism is classic criteria for UTI.criteria for UTI.

Serum Amylase/lipase : Serum Amylase/lipase : 1.Trauma1.Trauma

2. Pancreatitis2. Pancreatitis Serum electrolytes :Serum electrolytes : 1. Incarcerated inguinal hernia1. Incarcerated inguinal hernia

2. Intussuception2. Intussuception3. Intestinal volvulus3. Intestinal volvulus

Stool examination for worm infestation Stool examination for worm infestation

LAB STUDIES IN NON SURGICAL LAB STUDIES IN NON SURGICAL CAUSES OF ABDOMINAL PAINCAUSES OF ABDOMINAL PAIN

1-T4,TSH (HYPERTHYROIDISM)1-T4,TSH (HYPERTHYROIDISM) 2-GLUCOSE,KETONES(DKA)2-GLUCOSE,KETONES(DKA) 3-IONIZED 3-IONIZED

CALCIUM(HYPERCALCEMIA)CALCIUM(HYPERCALCEMIA) 4-SERUM LEAD (POISINING)4-SERUM LEAD (POISINING) 5-COTISOL (ADDISONE DISEASE)5-COTISOL (ADDISONE DISEASE) 6-PORPHYRINS(POPHYRIA)6-PORPHYRINS(POPHYRIA)

THANK YOUTHANK YOU Prof./MOUSTAFA RIZKProf./MOUSTAFA RIZK