July 2017 PDF

Proteinuria this month, babies’ poo, bedwetting and a bit more on paediatric hypertension.  Please do leave comments below.

Pooing and Constipation Throughout Infancy: Part One: What is Normal?

We welcome back Dr Marilyn Emedo for a series on pooing and constipation throughout infancy.  First Installment: What is Normal?

BREASTFED newborn babies stool anywhere between 7 times a day and once every 7-10 days. Stool is commonly “loose” in consistency and yellow in colour resembling “mustard seeds”. A reduction in frequency is typically seen from the 2nd month of life. 1

BOTTLE FED babies tend to open their bowels fewer times per day.

In 90% of normal term babies, meconium (intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water) is passed within 24 hours of birth and by 48 hours in nearly all normal babies.2

Preterm infants may take longer than this to first open their bowels; one study reported only 37% of preterm infants (25 -36 weeks gestation) open their bowels in the first 24 hours, and 32% are delayed over 48 hours. The ongoing frequency of stool output, and expected colour and consistency thereafter depends largely on what the baby is being fed.

This picture comes from http://www.breastfeedingmaterials.com where you can download a “diaper diary” with pictures of poo of all sorts of different colours and consistencies.

June 2017 PDF

Haematuria this month with links to an algorithmic Australian guideline on how to manage it in children, assessing paediatric hypertension, postural orthostatic tachycardia syndrome and the last for the time being in the “decoding the FBC” series – MCHC.

Please do leave comments below:

Mean Corpuscular Haemoglobin Concentration

(From June 2017 Paediatric Pearls Newsletter: Last in the “decoding the FBC” series by Dr Xanna Briscoe and Prof Irene Roberts for the time being)

Mean Corpuscular Haemoglobin (MCH) is the amount of haemoglobin per red blood cell.  MCHC is an estimate of the concentration of haemoglobin in a  given number of packed red blood cells.

MCHC = (Hb1 ÷ HcT2) x 100

Normal in children is 32-34% (adults 28-36%) depending on the lab

Chronic Anaemia

Iron Deficiency

Thalassaemia

spherocytosis

folic acid deficiency

Vit B12 deficiency

burns patients

sickle cell disease

 

What is PoTS? Is it an illness?

(From June 2017 Paediatric Pearls Newsletter)

It stands for Postural Orthostatic Tachycardia Syndrome, an autonomic disturbance

From support group POTS UK

leading to light-headedness, sweating, tremor, palpitations and near syncope in the upright position1

Definition:

  • Heart rate >120bpm on standing
  • HR increase > 40bpm after 10 minutes of standing (if aged 12-19 yrs. >30bpm if older)2

 

  • Despite our traditional concern with lying and standing blood pressures, it
    is the persistent tachycardia that characterises this health condition. Blood
    pressure may not change at all.
  • Recognised in age group 12 – 50, female to male ratio of 5:1
  • Can be primary (eg. adolescence) or secondary (eg. diabetes, hypermobility)
  • Different types and some are associated with a particular gene mutation
  • Can be diagnosed on tilt table or active stand test if necessary
  • Reassurance, a healthy lifestyle with sufficient aerobic exercise and fluid
    intake will help with symptoms and most adolescents grow out of it

 

URINALYSIS

(From June 2017 Paediatric Pearls Newsletter)

Also see:

Blood

  • Red or brown urine does not always mean blood
  • High false positive rate (eg. haemoglobinuria, myoglobinuria, concentrated urine, menstrual blood in the urine sample, rigorous exercise) so dipstick positive blood needs to be looked at under the microscope to accurately diagnose haematuria
  • False negative possible if specific gravity is < 1007
  • Significant haematuria is defined as ≥ 10 red blood cells (≥ 3 in adults) per high-power field in a properly collected and centrifuged urine specimen
  • Isolated microscopic haematuria in a well child only really needs further investigation after 3 positive samples over a period of a few months
  • Concomitant proteinuria, high BP or a palpable abdominal mass should be investigated promptly
  • Possible causes of haematuria in children:
    • UTI
    • Viral infections
    • Post streptococcal glomerulonephritis
    • Trauma
    • Henoch Schonlein Purpura
    • Wilm’s tumour (median age 3.5 years)

Resources:

Paediatric Hypertension (HTN)

(This appears in the June 2017 Newsletter, and continued from the April 2017 Newsletter)

Prevalence of HTN in children aged 8-17 years was approximately 2.2% between 2011 and 2014. Compare this with asthma prevalence of 9%, autism 1%, epilepsy 1%, and yet these all get much more air time than hypertension. Up to 30% of newly diagnosed hypertensive children and young people already have end organ damage, left ventricular hypertrophy in particular. 1

Hypertension: important points in the history:

  • Symptoms: lethargy, visual disturbances, headache, nausea, vomiting, failure to thrive
  • Past medical history: prematurity, central lines, UTIs, congenital heart disease
  • Family history: essential hypertension, polycystic kidneys, early CVS disease

BP measurement in babies and children is a skill which is often not done well:

  • Cuff size – you need a range of sizes. The bladder width needs to be at least 40% of the child’s arm circumference between olecranon and acromion and 80-100% of the circumference. A small cuff leads to an erroneously high BP measurement. Take BP in the arm, not leg (both if doing 4-limb BP obviously). At birth, BP measured in the legs is often lower than in the arms, equalises at 8/52 of age and after that leg blood pressure tends to be higher than in the arm.
  • Position – the child should ideally be lying down, relaxed, their limb at the same level as their heart.
  • Equipment – centile charts are put together using auscultation and a sphygmomanometer. Mechanical oscillometric devices are easy to use (be sure to still ensure correct cuff size) but are not as accurate which is why nephrologists always insist on a “manual reading”.

May newsletter – uploaded a little after the bank holiday…

May 2017 brings Tourette’s syndrome, child sexual exploitation, a paper on predicting serious bacterial infection and links to resources on recognising it.  Do leave comments below:

April 2017 PDF published

April 2017 brings children who were not brought, lucozade, hypertension, leucocytes in urine and macrocytosis.  I am not sure of the linking theme…  Do leave comments below.

Decoding the FBC (3): MCV

MCV- Mean Corpuscular Volume. (with thanks to Dr Xanna Briscoe and Prof Irene Roberts)

A measure of the size of the red blood cells.

Raised MCV- macrocytosis– may occur with or without anaemia. Physiological macrocytosis in the absence of anaemia occurs in neonates, especially those with Down syndrome, and during pregnancy.

Macrocytic anaemia- may be secondary to nutritional deficiencies in B12 and Folate leading to ineffective or abnormal erythropoiesis. This is easily diagnosed using simple blood tests. Where deficiency is excluded bone marrow examination may be required to identify rare causes such as myelodysplasia or Fanconi anaemia.

There are several drugs that may lead to macrocytosis, some of which are commonly used in the paediatric population. These include several chemotherapeutic agents, antibiotics and antiviral medications. It is also seen in congenital heart disease, hypothyroidism and Down Syndrome.

Additional investigations- guided by the history. It is important to check a reticulocyte count if a macrocytic anaemia is discovered. Reticulocytes are immature erythrocytes- which are large, and indicate increased erythropoiesis. Chronic reticulocytosis may falsely elevate the MCV. The absence of a raised reticulocyte count in the presence of severe anaemia suggests an inability of the bone marrow to produce red cells, eg due to inherited or acquired red cell aplasia.

Kaferle, Joyce, and Cheryl E. Strzoda. “Evaluation of macrocytosis.” American family physician 79.3 (2009).

Microcytosis– small red blood cells. Typically seen in iron deficiency anaemia; in the paediatric population at different ages the cause differs. In younger children and toddlers lack of supplementation may lead to deficiency. This is a particular issue in those that drink large volumes of cows milk as a substitute for iron containing foods. The main differential diagnosis is beta- or alpha-thalassaemia trait. Measurement of serum ferritin is the most useful test to identify iron deficiency- this will be low in iron deficiency and normal in beta- or alpha-thalassaemia trait.

In adolescence the pubertal growth spurt, and menorrhagia may be a causative factor. Further investigation will aid in determining the causes of microcytic anaemia (see below).

W Owen Uprichard, James Uprichard. Investigating microcytic anaemia. BMJ 2013;346:f3154

 

 

As published in April 2017 Paediatric Pearls newsletter…..

 

Increased MCV (macrocytosis) Decreased MCV (microcytosis)
Vitamin B12 DeficiencyFolic Acid DeficiencyAlcohol Abuse

Liver disease

Marrow aplasia

Myelofibrosis

Reticulocytosis

Hypothyroidism

Iron Deficiency AnemiaThalassemiaHemoglobinopathy

Anemia of Chronic Disease

Sideroblastic Anemia

Chronic Renal Failure

Lead Poisoning

Source: http://www.fpnotebook.com/HemeOnc/Lab/MnCrpsclrVlm.htm

 

MCV is expressed in femtoliters = 10^-15 liters

MCV cutoffs vary by age and by lab reference

 

MCV Normal Range:

  • Newborn: 95 to 121 fl
  • Ages 6 months to 2 years: 70 to 86 fl
  • Ages 12 to 18 years
  • Boys: 78 – 98
  • Girls: 78 – 102
  • Age over 18 years: 78 to 98 fl

 

MCV Cutoffs for Microcytic Anemia:

  • Age 1-2 years: <77 fl (CDC)
  • Age 3-5 years: <79 fl (CDC)
  • Age 6-11 years: <80 fl (CDC)
  • Age 12-15 years: <82 fl (CDC)
  • Age >15 years: <85 fl (CDC)
  • Recommended adult microcytic MCV cutoff varies

Some sources advocate MCV <78 and others <82

 

So, you’ve got the FBC back and it shows microcytic anaemia.  How can you work out which of the above factors is causative?

If you only asked for FBC and the child is more than 6 months old, try this:

Anaemia of chronic disease Thal trait (alpha OR beta) Iron deficiency anaemia Thal trait + IDA Haemoglobinopathy
Hb N / ↓ ↓ / ↓↓ ↓ / ↓↓ ↓ or ↑
MCV N / ↓ ↓ / ↓↓ ↓ / ↓↓ ↓ / ↓↓ ↓ or ↑
MCH N / ↓ ↓ / ↓↓ ↓ / ↓↓ ↓ / ↓↓ ↓ or ↑
RBC N/↑ N / ↓ N /  ↓ or ↑
RDW N N ↓ or ↑

 

Therefore a child of 6 months or older with hypochromic, microcytic anaemia with an increased RDW has presumed iron deficiency.  They could have thalassaemia trait as well….

 

If you asked for other tests or are at liberty to repeat the blood test, here are some suggested extra investigations and their interpretation:

 

Investigation Iron deficiency anaemia Thalassaemia trait Sideroblastic anaemia Chronic disease
Ferritin decreased Normal increased Normal/increased
Iron Decreased Normal Increased Decreased
TIBC increased Increased Normal decreased
transferrin decreased normal Normal Decreased
Hb electropheresis normal Β thalassaemia- raised A2

α trait- normal

normal normal