A bit more on babies’ stooling habits this month, NICE’s update on the epilepsies and glycosuria. Also the annual round up of useful blogs to get newcomers off to a good start in their paediatric practice. Please do leave comments below:
www.lifeinthefastlane.com has a great article describing the components of the humble urine dipstick and what we might learn from it. It is available here and I am going to borrow extensively from Dr Mike Cadogan’s work over the next few months but try to put a paediatric slant on it.
1) SPECIFIC GRAVITY (SG) – measures concentration of urine
Normal range varies by lab but roughly 1.005 to 1.030
< 1.005 – diabetes insipidus, fluid overload, pyelonephritis
> 1.030 – dehydration, glycosuria, SIADH
Falsely high in proteinuria, falsely low in alkaline urine
Glomerular filtrate has a pH of about 7.4 which is acidified to about 6 by the time it is passed as urine.
Causes of alkaline urine (⇑pH)
Causes of acidic urine (⇓pH)
Old sample, vegetarian diet, salicylate
overdose, UTI, citrus fruit ++, low carb diet
Metabolic/respiratory acidosis, diarrhoea, high
protein diet, DKA, cranberries, malabsorption
Nitrites on a dipstick test has a positive predictive value of 96% ie. it is highly likely that the child has a UTI. But the test’s negative predictive value is not so good (around 70%) ie. some children still have a UTI even though they have no nitrites in their urine. Why?
- 󠇫 only gram -ive bacteria convert nitrates to nitrites in urine; E coli, Proteus and Klebsiella are gram -ive, Enterococcus is not
- Can take 4 hours for this conversion to take place. Babies don’t hold urine in their bladder for that long.
The current NICE UTI guideline recommends microscopy and culture to rule out UTI in children younger than 3 but suggests that dipstick urinalysis is enough in older children. They are currently looking at new evidence to see if the dipstick result (leucocytes and nitrites) can be “trusted” in younger children. Update due to be published this year.
- Determines the presence of whole or lysed white cells in the urine (pyuria) by detecting leucocyte esterase activity.
- A positive leucocyte esterase test correlates well with pyuria. BUT, pyuria does not necessarily indicate a UTI. The white cells may be increased because of infection elsewhere. NICE “do not do recommendation”: Do not test urine if the infant or child has an obvious alternative source of infection.
- Conversely, a UTI diagnosis may be missed if a negative urinalysis dipstick is used to exclude UTI. Especially true in children less than 3 years old. NICE recommendation: if you suspect a UTI clinically, send urine for MC&S and do not rely on the dipstick result alone; we are supposed to diagnose a UTI if there is bacteriuria on microscopy, even without pyuria. Click here for further information on diagnosing UTI in children; it’s not quite as straight forward as you would hope.
- 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:
• Viral infections
• Post streptococcal glomerulonephritis
• Henoch Schonlein Purpura
• Wilm’s tumour (median age 3.5 years)
- The Royal Children’s Hospital in Melbourne has a sensible, easy-to-follow guideline for the management of children with haematuria
- Normal daily protein excretion ≤ 150mg/24 hours or 10mg/100mL. In nephrotic syndrome >3.5g/day is excreted. “Trace” positive results = 10 mg/100 ml or about 150 mg/24 hours (the upper limit of normal).
- Causes: transient or orthostatic (most common and benign), click here for summary of causes in children
- False Positive: Concentrated or alkaline urine (pH >7.5), trace residue of bleach, NaHCO3, cephalosporins
- False Negative: Dilute urine or acidic urine (pH <5) Use spot, early morning urine testing for a protein/creatinine ratio if the urine dipstick test result is 1+ protein or more. A 24 hour collection is impractical
|Dipstick protein reading||Protein excretion gm/24 hours||Protein excretion mg/dL|
|1+ (and above is abnormal)||0.2-0.5||30|
Ketones are not normally found in the urine. Produced by the liver as intermediate products of fatty acid metabolism, in normal states they will be completely metabolised. In “starvation” states eg. DKA or vomiting and reduced intake, fever, extreme cold and extreme exercise, the body metabolises increased fat to get the energy it needs to keep functioning. This results in ketonuria. ≥ ++ is abnormal. We often see ketones in the urine of unwell children in the ED. When glucose is present at the same time in the urine, diabetic ketoacidosis is the likely diagnosis.
(From the August 2017 newsletter)
Intraosseous needle insertion is pretty painful but not as painful as the subsequent infusion of the fluids. In the conscious patient, it is possible to infuse small volumes of lignocaine via the IO to provide pain relief. http://www.gosh.nhs.uk/health-professionals/clinical-guidelines/intraosseous-insertion provides a comprehensive guide to IO needle insertion and use. Appendix 1 of that document has a chart of how much lignocaine (lidocaine) to use according to the weight of the child. Volumes are tiny in the neonate.
(From the August 2017 newsletter)
In November 2016, NICE published its guidance on hypertension in adults which suggests 24 hour ambulatory blood pressure monitoring in the diagnosis of hypertension. ABPM should be measured in children before treating. It lessens the “white coat” effect and, if their BP is normal while asleep at night, the clinician can be fairly reassured that there is not likely to be a significant underlying cause for their hypertension.
Caveat:- you must get the cuff size right! The largest cuff which can fit on the arm should be used (2/3 the length of the upper arm, bladder 80-100% of the arm circumference). Small cuffs overestimate the blood pressure.
The centile charts for day and night blood pressures are available here at the bottom of the European consensus document. I have also uploaded them to the primary care guidelines tab. The 95th centile is the upper limit of normal. Values are gender specific and are set out according to heights and ages.
Lurbe E et al. 2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents. J Hypertens. 2016 Oct;34(10):1887-920
(From the August 2017 newsletter)
As of July 2017, http://www.rcpch.ac.uk/child-protection-evidence is housing all the evidence behind child safeguarding so painstakingly put together by the Cardiff Child PrOtection Systematic REviews project (CORE INFO) in collaboration with NSPCC. It’s a go-to page with links to national and international guidance and resources around safeguarding children.
NSPCC flyers currently available from the RCPCH site:
- Bruises on children
- Emotional neglect and emotional abuse in pre-school children
- Fractures in children
- Head and spinal injuries in children
- Neglect and emotional abuse in children aged 5-14
- Neglect and emotional abuse in teenagers aged 13-18
- Oral injuries and bites on children
- Thermal injuries on children
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.
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:
(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.
Normal in children is 32-34% (adults 28-36%) depending on the lab
folic acid deficiency
Vit B12 deficiency
sickle cell disease