Answer - Normal values
Feedback:  Being able to ascertain when results are normal is as important as recognising abnormal results.  This child may have lost a significant volume of blood but it has not affected his blood count.

Anaemia - Acute blood loss

Feedback: This child has a “normocytic” anaemia.  The MCV (mean corpuscular volume) and MCH (mean corpuscular haemoglobin) are normal.  In light of the history of trauma, acute blood loss is the most likely explanation.  If the child’s circulation is not compromised then a haemoglobin of this level shouldn’t cause any sequelae

Anaemia - Recent blood loss

Feedback:  This child has lost a significant volume of blood when he fell off his tricycle.  The key result here is the reticulocyte count which is high in combination with the normal MCV and normal MCH.  Reticulocytes are immature red blood cells and are increased whenever the rate of red cell production is increased.  This boy’s body has mounted a normal response in producing more blood cells in response to his blood loss.

Probable leukaemia

Feedback: Leukaemia is a malignant proliferation of white cell precursors within the bone marrow. The commonest type of leukaemia is acute lymphoblastic leukaemia (ALL) with peak onset at 5 year of age.

The most worrying result here is the WBC, which is markedly elevated, suggesting probable leukaemia which should be confirmed on a blood film looking for blast cells. The diagnosis also requires a bone marrow aspiration. A WCC of > 50 x 10^9 carries a worse prognosis in ALL.

The haemoglobin and platelet count are low here so you may have been tempted to go for anaemia or thrombocytopenia as an answer. These are low because the marrow is producing excessive white cells and is unable to maintain production of normal red cells and platelets.

Iron deficiency anaemia

Feedback: The clinical history may be a little deceptive but it is important to remember that investigations may reveal diagnoses you weren’t expecting.

Iron deficiency anaemia is very common in this age group and is the most common cause of anaemia in children. Common causes are: dietary deficiency, malabsorption (coeliac disease, cow’s milk intolerance, and inflammatory bowel disease), increased demand (prematurity, adolescence) and blood loss (recurrent epistaxis, menstrual losses in adolescence).

Further investigations would include iron studies such as a ferritin level. When seeing cases like this a differential to always keep in mind is the haemoglobinopathies (sickle cell, thalassaemia etc). The management of iron deficiency anaemia includes treating with elemental iron (1-2mg/kg three times daily), the parents should be warned that the child’s stools will appear dark/black. This boy should be followed up with a repeat FBC and reticulocytes to ensure the iron is having an affect. One would expect an increase of 1g/dl each week after starting iron therapy. Treatment should continue for a further three months after finding a normal Hb, to ensure iron stores are replenished.

Infection

Feedback: This FBC suggests an infection. The key result here is the raised WCC. A general rule of thumb is that if the neutrophil count is high it is likely to be a bacterial infection, if the lymphocyte count is high it is likely to be a viral infection. This is however, not an absolute.

Pertussis is an important differential as this can cause a high white count in children with fever and significant cough.

In this case, the history and examination points strongly to right lower lobe pneumonia, with such a high white cell count and localised infection, the organism is likely to be bacterial. This girl needs antibiotics. A chest X-ray may help confirm the diagnosis if there is diagnostic uncertainty, but is not absolutely necessary.

Thrombocytopenia

Feedback: The commonest cause of thrombocytopenia is Immune-mediated Thrombocytopenic Purpura (ITP). This is an immune-mediated destruction of circulating platelets. It usually affects children between the ages of 2-10 years. These children will commonly present with bruising, purpura or epistaxis (nose bleeds). The main concern is intracranial bleeding which affects 0.01-0.5% of those affected.

It is important to ensure that there are no features suggestive of leukaemia on a blood film.

Normal values

Feedback:  This is a hard question and requires a good understanding of newborn physiology.  Newborn babies commonly have high haemoglobin counts. From an infection point of view the normal WCC is reassuring.   The haemoglobin of newborn babies, at term, is predominantly fetal haemoglobin (HbF), which allows oxygen uptake at the placenta.  This is replaced over time with adult haemoglobin (HbA).

Polycythaemia

Feedback: Polycythaemia is an increase in the haemoglobin concentration of the blood. This can be due to either a decrease in the total volume of plasma (relative polycythaemia) or an increase in the volume of the red cells (absolute polycythaemia). The danger of a high Hb is that hyperviscosity is associated with hypoglycaemia, poor perfusion and cerebral, renal or IVC thrombosis.

Normal Biochemical Profile

Feedback: These results are normal. Your assessment of this child would therefore be entirely clinical. A child can still be dehydrated if the biochemistry results are normal. The signs of dehydration in a child are: reduced level of consciousness, dry mucous membranes, reduced skin turgor, tachypnoea, oliguria, sunken eyes, reduced capillary refill time, tachycardia, hypotension (a pre-terminal sign) and sudden weight loss.

Pre-renal renal failure

Feedback: This is pre-renal renal failure. A rough rule of thumb is: raised urea = pre-renal renal failure, raised creatinine = renal-renal failure. The kidneys in this case are hypo-perfused due to hypovolaemia (secondary to D&V) and are therefore unable to excrete the urea. This girl will need rehydration. Rehydration can be achieved by various routes in children: enteral (oral or NG tube) or parenteral (via an IV cannula).

Hypernatraemia

Feedback: This girl is hypernatraemic. There are multiple causes of hypernatraemia: dehydration, excessive sodium intake and diabetes insipidus (deficiency of ADH). In this case the history suggests dehydration as the most likely cause; this is supported by the raised urea.

The sodium level is a good reflector of the water balance of the body and is used regularly in paediatric medicine.

Hypovolaemia caused by diarrhoea and vomiting can cause both hyponatraemia (due to loss of sodium in diarrhoea) and hypernatraemia (due to fluid loss).

Diabetes Mellitus

Feedback: A (random) glucose level of >11mmol/l is considered diagnostic of diabetes mellitus. However, transient acute illness, stress, and steroid therapy can all also cause transient elevation of blood glucose, so in an asymptomatic child the hyperglycaemia must be confirmed on a different day. Where diagnostic doubt remains a formal glucose tolerance test may be helpful.

Diabetic Ketoacidosis

Feedback: This is diabetic ketoacidosis until proven otherwise. The key results here are: Raised glucose, low bicarbonate (this suggests that this girl is acidotic) and the urea and creatinine (this girl is dehydrated due to heavy glycosuria and associated diuresis). Senior medical staff should always be involved in management decisions in cases such as this.

The priorities in management are to firstly correct the hyperkalaemia and the initial shock and depleted circulating volume, The hyperkalaemia can be life-threatening. One then needs to gradually correct the metabolic decompensation over 36-48 hours and to avoid abrupt changes in plasma sodium concentration and osmolality (which can cause cerebral oedema). This girl also needs insulin in the form of an intravenous sliding scale. Subcutaneous insulin cannot be used as the peripheries will be shut down. .

Pyloric Stenosis

Feedback: Pyloric stenosis causes a hypochloraemic, hypokalaemic alkalosis (caused by repeated vomiting). K+, Cl- and H+ are all lost in the vomit. The vomiting is classically described as projectile. The hypertrophied pylorus is often palpable in the abdomen when giving the baby a feed (known as the test feed. Definitive management is surgical ligation of the hypertrophied pylorus (Ramstedt’s procedure).

Rickets

Feedback: Rickets usually results from deficient intake of vitamin D, or a nutritional deficiency of calcium. Mineralisation of the bone is poor. The bones are soft and the long bones are easily deformed.

In Rickets the calcium level is usually normal or low, with a reduced phosphate level and a raised alkaline phosphatase (a sign of bone resorption).

There are several forms of rickets: 1. nutritional rickets, 2. vitamin D dependent, 3. vitamin D resistant (hypophosphataemic) rickets.

You would do all of these, including giving paracetamol. An unexplained fever in a neonate (first 28 days of life) is a clinical sign that needs to be taken very seriously. You should therefore perform a septic screen which includes taking samples of blood, CSF and urine for analysis.

In sick/septic neonates one should also consider an ammonia level.

1. microscopy

The microbiology lab should be able to give you a microscopy result within an hour. A small sample of the urine is looked at under the microscopy to see if there are white cells or organisms in the urine.

No

This urine sample is very reassuring as there are <10x10⁶/l WCCs in the sample. A UTI is therefore very unlikely.

2 The sample was taken with an adhesive bag

The sample has epithelial cells in it because it was collected with an adhesive bag. Epithelial cells are present because urine samples are very difficult to obtain in infants of this age. Adhesive bags are attached to the perineal skin to obtain a sample. The “gold standard” method of obtaining urine is the “clean catch” method. This involves sitting the child on a sterile pot and waiting for the to pass urine. It takes patience and skill on the part of their parent/carer. Other sampling techniques include catheter sample or suprapubic aspirate (taken with a needle inserted above the pubis directly into the bladder).

1 microscopy

CSF is analysed in the same manner as urine. The microbiology lab should be able get a microscopy result within an hour.

yes

This child most likely has meningitis. The high WCC is very concerning.

Bacterial

This child most likely has bacterial meningitis. The key results are the low glucose level (<50% of blood glucose is abnormal). The white cell count (>5/mm3 abnormal) which shows the body is mounting a response against the infection. The sample shouldn’t be cloudy. The protein is on the high side of normal (this is very high in tuberculous meningitis). Polymorphs are neutrophils and suggest a bacterial cause of the meningitis.