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YR5 Chemical Pathology > Pre-recorded CP Summarised > Flashcards

Pre-recorded CP Summarised Flashcards

1
Q

What can metabolic acidosis be due to?

A

Increased H+ production: DKA

Decreased H+ excretion: Renal tubular acidosis

Bicarbonate loss: Intestinal fistula

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2
Q

What are causes of acute respiratory acidosis?

A

Decreased Ventilation: Neuromuscular weakness

Poor Lung Perfusion

Impaired Gas Exchange: COPD

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3
Q

What are causes of metabolic alkalosis?

A

H+ loss (e.g. pyloric stenosis)

Hypokalaemia: Loop diuretics, Conn’s

Ingestion of Bicarbonate

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4
Q

What are causes of respiratory alkalosis?

A

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

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5
Q

What is the equation for anion gap?

A

Na+K - Cl - HCO3

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6
Q

Give 7 causes of a high anion gap

A

Ketoacidosis: DKA, Alcoholic, Starvation

Uraemia: renal failure

Lactic acidosis: shock, ischaemia, sepsis

Toxins: Aspirin, Biguanides (metformin), Ethylene glycol

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7
Q

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

A

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

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8
Q

What is the osmolar gap?

A

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

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9
Q

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

A

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

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10
Q

What are 6 signs and symptoms of PKU?

A

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

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11
Q

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

A

Guthrie blood spot Test

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

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12
Q

What is congenital hypothyroidism? How is this screened?

A

Dysgenesis/ Agenesis of thyroid gland

TSH levels

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13
Q

What is cystic fibrosis? How is this screened?

A

Mutation in CFTR: viscous secretions + duct blockages

Immune reactive trypsin: if +ve DNA mutation detection

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14
Q

What is MCAD? How is this screened?

A

Fatty acid oxidation disorder
(reduced energy stores)

Acylcarnitine levels by tandem Mass Spectrometry

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15
Q

What is specificity?

A

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

True negatives / FP + TN

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16
Q

What is sensitivity?

A

probability someone WITH the disease will correctly test POSITIVE

True positives / TP + FN

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17
Q

What is positive predictive value?

A

probability someone who tests POSITIVE actually HAS the disease

True positives / TP + FP

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18
Q

What is negative predictive value?

A

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

True negatives / TN + FN

19
Q

Give 4 features of MCAD

A

Hypoglycaemia
Cardiomyopathy
Rhabdomyolysis
Low ketones

20
Q

Name 4 mitochondrial metabolic disorders

A

MELAS
Kearn’s
Sayre
POEMS

21
Q

Name 2 large molecule synthesis disorders

A

Peroxisomal disorders
Glycosylation disorders

22
Q

Name 1 disorder with defects in large molecule metabolism

A

Lysosomal disorders e.g. Tay Sachs disease

23
Q

Give 5 associated consequences of low birth weight

A

Respiratory distress syndrome (RDS)

Retinopathy of prematurity (ROP)

Intraventricular hemorrhage (IVH)

Patent ductus arteriosus (PDA)

Necrotizing enterocolitis (NEC)

24
Q

What is a cause of hyponatraemia in infants?

A

Congenital adrenal hyperplasia

25
Q

How should bilirubin be measured in neonates?

A

<24h or <35w gestation: Serum BR

> 24h or >35w gestation: Transcutaneous bilirubinometer

26
Q

What are signs of osteopaenia of prematurity?

A

Fraying, splaying + cupping of long bones.

27
Q

What is the biochemistry of osteopaenia of prematurity?

A

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

28
Q

What is the normal development of the nephrons?

A

Develop from week 6.

Start producing urine from 10w.

Functional maturity of GFR is not reached until ~2y

29
Q

Give 4 ways in which infantile renal function is deficient

A

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

30
Q

Give 3 common electrolyte disturbances in neonates

A

High insensible water loss (uncontrollable)

Hypernatraemia

Hyponatraemia

31
Q

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

A

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)

32
Q

What can cause hypernatraemia in neonates?

A

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

33
Q

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

A

Excess total body water due to excess intake

Rarely SIADH secondary to infection/ IVH

34
Q

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

A

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

35
Q

What are porphyrias?

A

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

36
Q

Why can porphyria cause neurovisceral or acute signs?

A

5-aminolaevulinic (5-ALA) acid is neurotoxic

37
Q

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

A

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

38
Q

List 4 features of acute porphyria

A

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

39
Q

What are 2 features of cutaneous non-acute porphyrias?

A

Skin lesions only
Blistering skin lesions + pigmentation

40
Q

What is porphyria cutanea tarda?

A

Commonest porphyria
Uroporphyrinogen decarboxylase deficiency

41
Q

Give 6 features of porphyria cutanea tarda

A

Photosensitivity
Facial hyperpigmentation
Hypertrichosis
Blistering
Milia
Scarring

42
Q

Which acute porphyrias cause skin lesions?

A

Hereditary Coproporphyria (HCP)
Variegate Porphyria (VP)

43
Q

How are the acute porphyrias differentiated?

A

AIP: No skin lesions

HCP & VP: Skin lesions

HCP + VP: Raised urine + faeces for porphyrins

Urine PBG: Raised in all three

YR5 Chemical Pathology (16 decks)

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