Paediatric Medicine copy
Terms in this set (90)
Define diabetic ketoacidosis
Diabetic ketoacidosis (DKA) is the build up of ketones in the blood as the result of an acute absolute insulin deficiency forcing the cells of the body to be starved of glucose and consequently revert to anaerobic metabolism.
How is diabetic ketoacidosis classified
- Glucose: >13.9 mmol/L
- Arterial pH: 7.25 to 7.30
- Bicarbonate: 15 to 18 mmol/L
- Mental status: alert
- Glucose: >13.9 mmol/L
- Arterial pH: 7.00 to <7.24
- Bicarbonate: 10 to <15 mmol/L
- Mental status: alert and/or drowsy
- Glucose: >13.9 mmol/L
- Arterial pH: <7.00
- Bicarbonate: <10 mmol/L
- Mental status: stupor and/or coma
Symptoms of hyperglycaemia in DKA
Symptoms of hyperglycaemia in both DKA include:
- Weight loss
Signs of hyperglycaemia in DKA
Signs of hyperglycaemic ketoacidosis includes:
- Volume depletion
- Dry mucous membranes
- Poor skin turgor
- Altered mental state
DKA patients may also exhibit....
- Nausea & vomiting
- Kussmaul respiration
- Acetone breath
- Abdominal pain
Outline the pathogenesis of type 1 diabetes
The pathogenesis of type I diabetes starts with...
1) Genetic susceptibility
Then you either have....
2) Immune response against normal/abnormal B cells
This then leads to...
3) Destruction of insulin secreting B cells
4) Impaired insulin secretion
5) Inability to uptake glucose in to cells
What are the supposed predisposing factors which can lead to the progression of Type I diabetes
Predisposing aetiologies include:
- Genetic inheritance
- Viral infection (enterovirus)
- Physical destruction of B cells
In diabetes what contributes to disrupt the acid-base balance
Uncontrolled diabetes can result in the production of ketone bodies as the acetyl CoA cannot enter the citric acid cycle. In conjunction, hyperglycaemia can occur due to the excess of glucose in the blood. This can lead to dehydration and the urinary excretion of ketones can be impaired. Systemic ketoacidosis can occur and the ketone bodies can reduce the pH of the blood.
Outline how hyperglycaemia causes polyuria
Hyperglycaemia causes an increase in the osmolarity of the blood. This cause fluid to move from the ICF to the ECF in an attempt to counteract the high glucose concentration. This results in cellular dehydration and increased volume in systemic circulation. As blood is filtered by the kidneys they are unable to reabsorb all the glucose, as per normal, and therefore glucose is excreted in the urine. This causes polyuria because an osmotic gradient is established, pulling water to be excreted with the glucose.
What are the names given to clusters of exocrine cells and the groups of endocrine cells in the pancreas
Exocrine - Islets of Langerhans.
Endocrine - Accini.
Clinical significance of C-peptide
Secreted in equimolar quantities with insulin therefore can measure endogenous insulin secretion.
If you were to measure the C-peptide in a patient with newly established diabetes, what would the level tell you
If the C-peptide were low, that would suggest that the patient is unable to make C-peptide and thus insulin = type 1 diabetes.
If the C-peptide were high, that would suggest insulin resistance = type II diabetes.
Briefly, why would we measure the C peptide level rather than the insulin level
Because the insulin concentration varies within the concentration. The liver concentrates plasma insulin depending upon the bodies nutritional state. In the other hand, I guess C- peptide levels are more stable.
Pathway of insulin release
1) Increase blood glucose [ ]
2) GLUT 2 transports glucose into B cell
3) Glycolysis leads to ATP generated inside the cell which close ATP-sensitive K+ channels, 3) Raised intracellular [K+] increases intracellular positive charge
4) Depolarisation the membrane
5) Calcium influx which stimulates insulin secretion
What inhibits insulin secretion
Inhibitors of insulin secretion include:
- Sympathetic activation (Adrenaline)
- Low blood glucose [ ]
- Somatostatin inhibits the release of both insulin and glucagon
What are some of the signs you would look for in an infant which may be suggestive of type 1 diabetes
Suggestive features include:
- Candida infection around nappy
Outline the initial investigations which you are going to perform in a patient with suspected type I diabetes
1) BSL (hyperglycaemic / ketones)
2) Urinalysis (ketones)
3) ABGs (metabolic acidosis)
4) EUCs (low Na, anions, high K & anion gap)
5) Lactate (DDx for lactic acidosis)
6) FBC (Leukocytosis in hyperglycaemia)
What are the main goals in treating patients with diabetic ketoacidosis
The main goals of treatment are:
- Restoration of volume deficits
- Resolution of hyperglycaemia
- Fix ketosis/acidosis
- Correction of electrolyte abnormalities
- Treatment of the precipitating events - Prevention of complications
Why should a hypoglycaemic patient not be hypokalaemic when initiating insulin therapy
Potassium level should be >3.3 mmol/L [>3.3 mEq/L] before initiation of insulin therapy; use of insulin in a patient with hypokalaemia may further reduce potassium and lead to respiratory paralysis, cardiac arrhythmias, and death.
Outline the initial supportive therapy for DKA
Initial supportive therapy includes:
- Airway optimisation
- Isotonic fluids 1-1.5L/hr
- Vasopressor support
- Maintain MAP >65
How should fluid managed be titrated in a patient with DKA. What signs would indicate adequate fluid replacement
The presence of orthostatic hypotension or supine hypotension with dry mucous membranes and poor skin turgor indicates severe volume depletion, which should be treated by infusion of 0.9% NaCl at the rate of 1.0 L/hour until signs of severe volume depletion are resolved.
No glucose containing solutions should be administered until BSL is <12mmol/L. Sodium levels will also determine which fluid is used. How would fluid management change in a patient who is hyper versus hyponatramic with DKA
Changes in management include:
In hyponatraemic patients:
- 0.9% NaCl
- 250 to 500 mL/hour
In hypernatraemic or eunatraemic patients:
- 0.45% NaCl
- 250 to 500 mL/hour
When the plasma glucose reaches 11.1 mmol/L.....
- Add 5% dextrose to current NaCl infusion
(American Diabetes Association 2006)
Outline the insulin management of a patient with DKA
Patients should receive subcutaneous injection of rapid-acting insulin:
- Initial dose of 0.3 units/kg
- 0.2 units/kg 1 hour later
- 0.2 units/kg every 2 hours until blood glucose becomes <13.9 mmol/L
(ADA - Diabetes Care 2009)
Outline the management of serum potassium in a patient with DKA. what are the goals in this form of management
Insulin therapy and correction of acidaemia and hyperosmolality will drive potassium into cells, which may cause serious hypokalaemia. The goal, therefore, is to correct the actual potassium deficits and thereby prevent fatal complications of hypokalaemia, including respiratory paralysis and cardiac dysrhythmia.
Bicarbonate therapy may be used in adult patients with an arterial blood pH <7 in DKA. What is the dose which you would consider in these patients
100 mmol sodium bicarbonate in 400 mL sterile water with 10 mmol (10 mEq) potassium chloride (KCl) may be administered over 1 hour until pH is >7.0.
Microvascular complications of DM
• Retinopathy, cataract - Impaired vision
• Nephropathy - Renal failure
• Peripheral neuropathy - Sensory loss
• Motor weakness
• Autonomic neuropathy - Postural hypotension
• Gastrointestinal problems (gastroparesis; altered bowel habit)
• Foot disease - Ulceration
Macrovascular complications of DM
• Coronary circulation - Myocardial ischaemia/infarction
• Cerebral circulation - Transient ischaemic attack
• Peripheral circulation - Claudication
What are the three typess off diabetes and what are some of the features of each
3 Types include:
1. Type I - autoimmune, earrly age onset, prone to ketoacidosis
2. Type II - associated with obesity, middle agee onsset
3. Gestational - insulin resistance which resides post partum, more susceptible to Type II later in life. Macrosomia usually present
Outline four major components you would include in the management plan of a severely diabetic patient
Components of a diabetic management plan can include:
1. Lifestyle Factors - Diet, Exercise, Hygiene, Self‐care
2. Medications - Review & Manage interactions, Education
3. Immunisations - Annual influenza shot, Pneumococcal
4. Investigations - BSL, lipids, urine
Describe the common characteristics of the secretions in cystic fibosis
Thick, dehydrated sticky mucous that clogs up organs
and is a potential breeding ground for infection. No Cl- transporters on apical surface.
What is the pathophysiology of cystic fibrosis
Mutations in CFTR result in abnormal salt transport by epithelial cells, resulting in thick, sticky secretions.
Delta F508 is the gene responsible for the pathogenesis of cystic fibrosis. What happens to the gene in CS
(Change of Phe (F) amino acid at position 508 ) 70% of severe cases of CF.
Glands affected by Cystic fibrosis PRIGS
What are the main organ effects to the pancreas in cystic fibrosis
Organs systems effected:
- Blockage of exocrine ducts
- Early activation of pancreatic enzymes
- Eventual autodestruction of the exocrine pancreas
N.B. Therefore, most patients require supplemental pancreatic enzymes. This is the main reason why cystic fibrosis patients fail to thrive.
What are the main organ effects to the bowels in cystic fibrosis
Organs systems affected:
- Thick mucus
- Bulky stools
- Lead to intestinal blockage
N.B. Therefore, most patients require laxatives and high dietary fibre.
What are the main organ effects to the respiratory system in cystic fibrosis
Organs systems effected:
- Mucus retention
- Chronic infection
- Inflammation that eventuate in the destruction of lung tissue
N.B. Therefore, most patients need to be on antibiotics and have daily chest physio.
What do the assays test for in the neonatal assessment of a newborn
The two assays used for newborn screening are serum immunoreactive trypsin (IRT) and DNA analysis for mutations in CFTR.
What is the sensitivity of the IRT testing
The initial IRT test is approximately 80 percent sensitive for detecting CF using typical cutoff values, and additional patients are not diagnosed through the IRT/IRT protocol if a second sample is not returned for testing.
What is the next stag in investigation for a child who screens positive for cystic fibrosis
Infants with positive CF newborn screening results should undergo sweat chloride testing to determine whether they have CF.
For optimal accuracy, sweat testing should be performed. When should this be performed
When the infant is at least two weeks of age and weighs >2 kg then it would be suitable to do sweat testing.
What is the rationale for screening for cystic fibrosis
The rationale for newborn screening is that early detection of CF may lead to earlier intervention and improved outcomes because affected individuals are diagnosed, referred, and treated earlier in life as compared with individuals who are diagnosed after presenting with symptomatic CF.
Briefly outline the
pathophysiology of malabsorption in cystic fibrosis
Contributing factors to malabsortion include:
1. Reduced chloride secretion:
- Excess water in the gut
- Increase vicious secretion from pancreas
2. Reduced bicarbonate secretion by the pancreas:
- Endogenous & exogenous pancreatic enzymes can't work at their optimal pH
Both these factors contribute to malabsorption.
Outline the timing of the following factors in normal growth, genetics, nutrition and hormones
The influence of nutrition and the intrauterine environment effect growth parameters at the time of birth and during the first month of life, whereas genetic factors have a later influence in life, especially in puberty.
Briefly outline the NHMRC
dietary guidelines for children and adolescents
NHMRC guidelines for children and adolescents:
Consume plenty of:
- Wide range of nutritious foods
- Cereals, legumes and fruits
- Wholegrain breads, rice, pasta
Include in your diet:
- Lean meat, fish and poultry
- Dairy, such as milks, yoghurts
- Low fat milk in children <2 years - Saturate fat intake
- Salt intake
- Sugars and sweets
Intrauterine growth restriction refers to the poor growth of a baby while in the womb. Specifically, it refers to a foetus whose weight is below the 10th percentile for its gestational age. Outline the pathophysiology of intrauterine growth restriction
Intrauterine growth restriction is due to either:
- Nutritional deficiency
- Lack of uterine compliance
- Small restricting pelvis
List the key clinical features of protein malabsorption
Clinical features include:
- Growth failure
- Muscle wasting
- Hypoproteinaemic oedema
Outline the parameters that are measured in the assessment of a child's nutritional status using anthopometry and physical examination methods
Physical examination and anthropometry measurements include:
• Detail height, length and weight
• Head circumference (up to 3 years)
• Assess growth velocity
• Skinfold thickness
• Midarm circumference
List the common 4 long-term
complications of prematurity
Long-term complications of prematurity include:
1. Retinopathy (abnormal vascularisation and fibrous scaring)
2. Chronic lung disease (barotrauma) 3. Growth failure (gastrointestinal/ endocrine)
4. Neurodevelopmental delay (CP, retardation)
Outline the general health promoting advice a doctor should provide to a woman seeking to become pregnant
Health promotion advice includes:
- Nutrition: Folic acid, iron, omega-3
- Weight: Healthy BMI
- Drugs: Eliminate unsafe medications
- Smoking: Growth retardation
- Sex: STI prevention, hepatitis, HIV
- Exercise: Improved cardiac function
- Avoid deli foods: Listeria Monocytogenes
Outline the first and second steps in sexual development of girls through puberty
1st step: (>10years)
- Pubic hair
- Growth spurt
- Increase in hip size
- Armpit, and leg hair growth
2nd Step: (typically 2 years later)
- 1st menstration (menarche)
During puberty, endocrine glands produce hormones that cause body changes and the development of secondary sex characteristics. Outline the hormones responsible for secondary sexual characteristics
In girls, the ovaries begin to increase production of oestrogen and other female hormones.
In boys, the testicles increase production of testosterone.
True or False. Growth is seasonal, with growth velocities increased during the spring and summer months
True. Normal human growth can correlate with nutrition and seasons.
True or False. Human growth increases steadily in most children
False. Normal human growth is pulsatile; periods of rapid growth ("growth spurts") are separated by periods of no measurable growth.
Outline the "Rules of Five" for predicting normal growth rates in children
Rules of Five include:
● 25cm/year during the first year
● 10cm/year between 1-4 years
● 5cm/year between 4-8 years
● 5cm/year between 8-12 years
When does the growth chart stop measuring head circumference and weight-for-length in an infant and switch to plotting BMI
Head circumference and weight-for-length are plotted between birth and two years of age, and BMI after two years of age.
What are the factors which are measured in the CDC/WHO Growth Charts for children aged zero to two years
For boys and girls aged zero to two years, the charts plot:
● Head circumference-for-age
What are the factors which are measured in the CDC/WHO Growth Charts for children aged two to twenty years
For boys and girls aged two to twenty years, the charts plot:
Bone age is the degree of maturation of a child's bones. As a person grows from foetal life through childhood, puberty, and finishes growth as a young adult, the bones of the skeleton change in size and shape. These changes can be seen by x-ray, what are they
The main thing which is looked for in determining bone age is the number of ossification centres present in various bones. These can then be plotted to with tables to give an average bone-age.
Explain what is meant by height velocity
• Speed of growth (i.e. growth/time)
• 0-12months measured as cm/month
• 1-10 years measured as cm/year
What value of height velocity should be closely monitored in a pre-pubertal paediatric patient
A prepubertal child whose height velocity is <2 inches/year (<5 cm/year) should be monitored closely.
The two most common causes of short stature beyond the first year or two of life
The two most common causes of short stature beyond the first year or two of life are variants of normal growth:
- Familial short stature
- Delayed (constitutional) growth
Differential features between familial short stature and constitutional short stature
What is height age
The age that corresponds to the child's height when plotted at the 50th percentile on a growth chart.
Mid-parental height is somewhat described as the height the child is likely to reach depending on the height or their parents. What are the calculations used for girls and boys
Boys mid-parental height:
• [Paternal height + (Maternal height + 13cm)] / 2
Girls mid-parental height:
• [Maternal height + (Paternal height - 13cm)] / 2
List the normal variants of growth which can give short stature
Normal variants of stature include:
- Constitutional delay of growth
- Familial short stature
- Idiopathic shortness (tracks percentiles)
- Small for gestational age infants with catch-up growth
List the pathological variants of growth which can give short stature
Pathological variants of stature include:
- Glucocorticoid therapy
- Rheumatological (juvenile idiopathic arthritis JIA)
- Gastrointestinal disease (Crohn's)
- Renal (CKD - calcium loss)
- Pulmonary (cystic fibrosis)
- Cardiac (VSD)
- Immune (leukaemia)
- Endocrine (hypothyroidism)
- Genetic (Turner, Noonan, Russell-Silver)
- Skeletal (Achondroplasia, Hypochondroplasia, Spondyloepiphysial dysplasia)
Tanner stages of breast development in girls
Stages in breast development in girls:
Stage 1: No palpable breast tissue.
Stage 2: Breast bud, elevation of papilla and enlargement of the areolar diameter.
Stage 3: Enlargement of the breast, without separation of areolar contour
Stage 4: Areola and papilla project above the breast
Stage 5: Recession of the areola to match the contour of the breast
Tanner stages of development in pubic hair in girls
Stages of development in pubic hair in girls:
Stage 1: Prepubertal with no pubic hair
Stage 2: Sparse, straight hair along the lateral vulva
Stage 3: Darker, coarser, and curlier hair extending over the mid-pubis
Stage 4: Hair does not extend to the thighs
Stage 5: Hair extending from thigh to thigh
Tanner stages of pubic hair development in boys
Stages of pubic hair development in boys: Stage 1: Prepubertal, with no pubic hair Stage 2: Sparse, straight pubic hair along the base of the penis
Stage 3: Darker, coarser, and curlier hair extending over the mid-pubis
Stage 4: Hair does not extend to thighs
Stage 5: Hair extending from thigh to thigh
What is the earliest stage of male maturation in puberty
The earliest stage of male maturation, which has a mean duration of six months, is an increase in testicular volume.
How is testicular volume measured
Testicular volume is typically measured using the Prader orchidometer, a series of three-dimensional ellipsoids with a volume from 1 to 25 mL or more.
Describe the sequence of events in puberty and what event tends to correlate with peak height velocity and is thus considered parallel with female menarche
Sequence of events in male puberty include:
1. Increased testicular volume
2. Pubic hair
3. Sperm in urine / wet dreams
4. Stage 5 pubic hair
5. Musculoskeletal maturity
The age at onset of puberty and the age of menarche are influenced by several factors. List some of these influencing factors
Influencing factors include:
- Genetics (majority of the variability)
- Overall health
- Body weight
- Environmental exposures
What is precocious puberty
Precocious puberty is the onset of pubertal development at an earlier age than is expected based upon established normal standards.
What are the ages which are used to determine precocious puberty
Precocious puberty is usually defined as the onset of secondary sexual development before the age of eight years in girls and nine years in boys
What are the questions a doctor needs to figure out in a child presenting with early sexual development
The clinician faced with a child who presents with early sexual development should consider the following questions:
1. Is the child too young?
2. Causes of early sexual development?
3. Is therapy indicated?
Activation of which endocrine axis stimulates the progression in to pubertal changes
Children enter puberty when the suppression is released, which permits re-activation of the hypothalamic-pituitary-gonadal axis.
Outline the classification of precocious puberty
Classification — Precocious puberty can be classified based upon the underlying pathologic process, these include:
1. Gonadotropin-dependent precocious puberty
- Early maturation of the HPG axis
2. Gonadotropin-independent precocious puberty
- Excess secretion of sex hormones
3. Incomplete precocious puberty
- Increased adrenal androgen production (premature adrenarche)
Gonadotropin-dependent precocious puberty (central precocious puberty) is caused by early maturation of hypothalamic-pituitary-gonadal axis. What are some causes of this
1. CNS lesions
- Hamartomas/astrocytomas mediate release of GnRH
2. CNS irradiation
- Scaring of HPG axis
- Prader-Willi syndrome
4. Primary hypothyroidism
- Development regresses with thyroxine
5. Sex hormone exposure
Gonadotropin-independent precocious puberty (also known as peripheral precocious puberty or pseudo-precocious puberty) is caused by excess secretion of sex hormones (estrogens or androgens) derived either from the gonads or adrenal glands or from exogenous sources. What are some causes of this
- Ovarian cysts/ tumours
- Leydig cell tumours
- Human chorionic gonadotropin (hCG) secreting germ cell tumours
- Exogenous oestrogen exposure
- Pituitary gonadotropin-secreting tumours
Incomplete precocious puberty is the early development of secondary sexual characteristics and usually is a variant of normal puberty. What are the diagnostic features of this condition
Key features of premature thelarche are:
● Isolated breast development, either unilateral or bilateral
● Absence of other secondary sexual characteristics
● Normal linear growth
● Normal bone age
Gonadotropin dependent precocious puberty (GDPP) can be distinguished from Gonadotropin independent precocious puberty (GIPP) by measuring LH levels. What LH levels correspond with which condition
LH levels distinguish...
- GDPP: LH levels are often elevated into the pubertal range and show a pubertal (heightened) response to GnRH stimulation.
- GIPP: LH level is low at baseline and fails to respond to GnRH stimulation.
Define delayed puberty
Delayed puberty is defined clinically by the absence or incomplete development of secondary sexual characteristics bounded by an age at which 95 percent of children of that sex and culture have initiated sexual maturation.
What ages typically correspond for the upper 95th percentile for puberty onset
For boys it is 14 (an increase in testicular size being the first sign) and for girls is 12 (breast development being the first sign).
Explain primary hypogonadism by relating it to the circulating levels of LH and FSH
Primary hypogonadism is characterised by high levels of luteinising hormone (LH) and follicle-stimulating hormone (FSH).
Explain secondary hypogonadism by relating it to the circulating levels of LH, FSH and GnRH
Secondary hypogonadism is characterised by low to normal concentrations of LH and FSH, and typically is caused by impaired secretion of hypothalamic gonadotropin-releasing hormone (GnRH).
What is the short-term hormonal therapy which can be initiated in boys and girls with delayed puberty
Short-term hormonal therapy with testosterone in boys and with oestrogen in girls may be appropriate when the pubertal delay is severe or the patient has psychosocial concerns.
Causes of primary hypogonadism
Primary hypogonadism i.e. High FSH and LH:
- Chromosomal abnormalities (Turner syndrome - 45,XO; Klinefelter syndrome - 47,XXY)
- Anorchia (vanishing testis)
- Iatrogenic (surgery, chemo, radiation)
Causes of secondary hypogonadism
Secondary hypogonadism - Low to normal FSH and LH:
- Isolated GnRH deficiency (Kallmann)
- GnRH deficiency (Prader-Willi)
- Idiopathic pituitary hormone deficiencies
- Congenital malformations
- Tumors (gliomas, astrocytomas
- Constitutional delay from chronic disease
Constitutional delay from malnutrition (Cushing's, Anorexia)
- Head trauma
- Pituitary apoplexy
- Drugs - Marijuana
Outline the key results in investigations used to determine short stature in a child
Short stature can be determined by:
- Height below the 2.3rd percentile (≤-2 SD)
- Height velocity <5cm/year in those >1year
- Projected height is greater than 8.5 cm (2 SD) below the midparental height
- Delayed bone age
Outline the components of the history and examination of a child with short stature
The history and physical examination should include:
• Family history of growth and pubertal onset
• Review of systems for features suggestive of gastrointestinal, pulmonary, immunologic, or other systemic disease
• Dysmorphic features, especially webbed neck, cubitus valgus, and absent puberty in girls (suggests Turner syndrome) and limb length discrepancies.
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