Pre-recorded CP Summarised Flashcards by Georgia Leggett

What can metabolic acidosis be due to?

Increased H+ production: DKA

Decreased H+ excretion: Renal tubular acidosis

Bicarbonate loss: Intestinal fistula

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What are causes of acute respiratory acidosis?

Decreased Ventilation: Neuromuscular weakness

Poor Lung Perfusion

Impaired Gas Exchange: COPD

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What are causes of metabolic alkalosis?

H+ loss (e.g. pyloric stenosis)

Hypokalaemia: Loop diuretics, Conn’s

Ingestion of Bicarbonate

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What are causes of respiratory alkalosis?

Due to Hyperventilation:
Voluntary
Artificial ventilation
Stimulation of respiratory centre: high altitude

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What is the equation for anion gap?

Na+K - Cl - HCO3

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Give 7 causes of a high anion gap

Ketoacidosis: DKA, Alcoholic, Starvation

Uraemia: renal failure

Lactic acidosis: shock, ischaemia, sepsis

Toxins: Aspirin, Biguanides (metformin), Ethylene glycol

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What is the normal range for anion gap? What is the main contributor of the anion gap?

14 - 18mmol/l
Almost entirely contributed by albumin (beware in hypoalbuminaemia)

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What is the osmolar gap?

Osmolarity (measured) - Osmolarity (calculated)
Normal <10

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What is phenylketonuria (PKU)? What is the inheritance pattern? How is this screened?

Phenylalanine hydroxylase deficiency
Autosomal recessive
Leads to accumulation of toxins:
Phenylalanine levels

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What are 6 signs and symptoms of PKU?

Developmental delay
Fair hair + blue eyes
Learning difficulties
Seizures, typically infantile spasms
Eczema
‘musty’ odour to urine + sweat

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What test is performed at 5-8 days of life? What does this screen for?

Guthrie blood spot Test

Phenylketonuria
Congenital hypothyroidism
Cystic fibrosis
Sickle cell disease
MCAD (medium chain acylCoA dehydrogenase) deficiency

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What is congenital hypothyroidism? How is this screened?

Dysgenesis/ Agenesis of thyroid gland

TSH levels

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What is cystic fibrosis? How is this screened?

Mutation in CFTR: viscous secretions + duct blockages

Immune reactive trypsin: if +ve DNA mutation detection

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What is MCAD? How is this screened?

Fatty acid oxidation disorder
(reduced energy stores)

Acylcarnitine levels by tandem Mass Spectrometry

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What is specificity?

probability (in %) that someone WITHOUT the disease will correctly test NEGATIVE

True negatives / FP + TN

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What is sensitivity?

probability someone WITH the disease will correctly test POSITIVE

True positives / TP + FN

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What is positive predictive value?

probability someone who tests POSITIVE actually HAS the disease

True positives / TP + FP

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What is negative predictive value?

probability someone who tests NEGATIVE actually DOES’NT have the disease

True negatives / TN + FN

Give 4 features of MCAD

Hypoglycaemia
Cardiomyopathy
Rhabdomyolysis
Low ketones

Name 4 mitochondrial metabolic disorders

MELAS
Kearn’s
Sayre
POEMS

Name 2 large molecule synthesis disorders

Peroxisomal disorders
Glycosylation disorders

Name 1 disorder with defects in large molecule metabolism

Lysosomal disorders e.g. Tay Sachs disease

Give 5 associated consequences of low birth weight

Respiratory distress syndrome (RDS)

Retinopathy of prematurity (ROP)

Intraventricular hemorrhage (IVH)

Patent ductus arteriosus (PDA)

Necrotizing enterocolitis (NEC)

What is a cause of hyponatraemia in infants?

Congenital adrenal hyperplasia

How should bilirubin be measured in neonates?

<24h or <35w gestation: Serum BR >24h or >35w gestation: Transcutaneous bilirubinometer

What are signs of osteopaenia of prematurity?

Fraying, splaying + cupping of long bones.

What is the biochemistry of osteopaenia of prematurity?

Calcium within reference range Phosphate <1mmol/L ALP >1200 U/l (10 x adult ULN)

What is the normal development of the nephrons?

Develop from week 6. Start producing urine from 10w. Functional maturity of GFR is not reached until ~2y

Give 4 ways in which infantile renal function is deficient

Low GFR for surface area: slow excretion Less reabsorption due to short proximal tubule Reduced conc. ability due to short loops of Henle + distal collecting ducts Persistent Na loss due to distal tubule being relatively aldosterone-insensitive

Give 3 common electrolyte disturbances in neonates

High insensible water loss (uncontrollable) Hypernatraemia Hyponatraemia

Why is there high insensible water loss in neonates? (4)

High SA to body weight ratio Skin blood flow is increased Metabolic/ respiratory rate is higher than adults Transepidermal fluid loss (less good barrier as immature)

What can cause hypernatraemia in neonates?

Common. Can be a marker of dehydration or overly concentrated milk formula

What can cause hyponatraemia in first 4-5 days of life

Excess total body water due to excess intake Rarely SIADH secondary to infection/ IVH

What can cause hyponatraemia after first 4-5 days in a neonate?

Loss of Na due to immature tubular function in patients on diuresis

What are porphyrias?

7 disorders caused by deficiency in enzymes, involved in haem biosynthesis, leading to build up of toxic haem precursors.

Why can porphyria cause neurovisceral or acute signs?

5-aminolaevulinic (5-ALA) acid is neurotoxic

What are 3 features of Acute Porphyria? (acute intermittent porphyria)

Autosomal dominant HMB synthase deficiency NO cutaneous manifestations due to absence of porphyrinogens

List 4 features of acute porphyria

Painful abdomen Seizures Peripheral neuropathy Psychosis Port urine Muscle weakness Constipation Urinary incontinence.

What are 2 features of cutaneous non-acute porphyrias?

Skin lesions only Blistering skin lesions + pigmentation

What is porphyria cutanea tarda?

Commonest porphyria Uroporphyrinogen decarboxylase deficiency

Give 6 features of porphyria cutanea tarda

Photosensitivity Facial hyperpigmentation Hypertrichosis Blistering Milia Scarring

Which acute porphyrias cause skin lesions?

Hereditary Coproporphyria (HCP) Variegate Porphyria (VP)

How are the acute porphyrias differentiated?

AIP: No skin lesions HCP & VP: Skin lesions HCP + VP: Raised urine + faeces for porphyrins Urine PBG: Raised in all three