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Self-assessment questions
Current
Paedia/rics
0 1999 Harcourt
(I 999) 9, 70~-73
Brace & Co. Ltd
Self-assessment questions
M. Wagstaff
Question
night asking for drinks. She was passing plenty of urine, but was not enuretic. She is otherwise well and has a 2-month-old brother.
1
A lo-year-old boy presented with his first afebrile convulsion. His parents describe a 5-minute generalized tonic clonic convulsion, from which he fully recovered 90 minutes later. He is developmentally normal, with no previous medical history of note. He has become upset recently over his continued bedwetting, and his GP recently prescribed a ‘night-time tablet’, his parents say, to help. Since starting he has been dry by night.
Investigations
A water deprivation test showed the following Serum osmolality 292 mosmol/l Urine osmolality 930 mosmol/l
A. What is the likely cause of the fit? B. What investigations are necessary? C. What is the treatment? Question
A. What further investigations are necessary? B. What is the likely diagnosis?
2
Question
A 2-year-old boy with severe Hurlers Syndrome is seen in Outpatients. He has global developmental delay and behavioural problems. He is thought to be a little pale, and the blood results are as follows:
A. What is the diagnosis?
B. What other investigations are necessary? C. What treatment is required? 3
A 4-year-old girl presented with ‘excessivethirst’. She
was drinking 3 litres during the day and waking at
Dr Miles Wagstaff, Specialist Registrar United Hospital, Bath BAI 3NG, UK. Correspondence
and requests
in Paediatrics,
Tar olTprints
4
A 2-year-old boy is referred for a medical examination by his GP and social services,after a deformity of his right ankle was noted. The parents had no explanation to offer. He is still breast fed and there have been concerns raised previously about his mildly delayed motor development. He is one of three children who live with their parents and other families in a large isolated house. The Health Visitor, who is not allowed to visit, describes their lifestyle as ‘alternative’. On examination he is well grown, with no signs of trauma. He has swollen wrists and an obvious abnormality of his right ankle. X-rays are taken (see Figures I and 2).
Hb 3.9 g/d1 MCV 54 fl WCC 4.1 x 10^9/1 Plat 206 x 10”9/1
Question
Sodium 134 mmol/l Potassium 4. I mmol/l Calcium 2.2 mmol/I Urinalysis ~ culture negative
A. What features are shown on the X-rays and what is the diagnosis? B. How would you confirm the diagnosis? C. What is the treatment, and what is the major danger of treatment?
Royal
to M W.
70
Self-assessment auestions
Fig. 1
Question 5 A previously well, term baby suffers a cardiac arrest on the postnatal ward on day 2 of life. Resuscitation efforts are successful. Fig. 2
A. What does her ECG show? B. With what is this associated? C. What are the treatment options?
Question 6 A 3-year-old 3 month stay and has lost examination phadenopathy
girl presents with a fever 2 weeks after a with rclativcs in Africa. She is not eating weight. She has developed a cough. On she is pyrexial, has generalised lymand a palpable spleen (see Figure 3).
Blood tests show:
Hb 11.3 g/d1 WCC 12.4x IO”911 Pit 244 x 10”9/1 Malaria slide negative
A. What are the main differential diagnoses? B. How would you confirm the diagnosis?
Fig. 3
71
12
Current Paediatrics
Self-assessmentanswers
Answer 3
Answer 1
A. Serum glucose. A. Serum urea and creatinine. B. Psychogenic polydipsia.
A. Hyponatraemic fit with water overload, secondary to medication: He had been prescribed ‘Desmotabs’ (Vasopressin) 3 weeks earlier to control his enuresis. The risk is from water overload, and the information sheet stressesthe importance of avoiding excessiveevening drinking. As with any medicine, there is always a risk of overdose, intentional or accidental, although not in this case. B. Serum electrolytes - showing low sodium (Na 121 mmol/l) C. Water restriction. Stop medication. Water restriction is usually sufficient to correct hyponatraemia if the cause is water overload, especially in this case when the source of the water overload is removed (i.e. stop medication). Regular checking of the serum electrolytes confirms the normalisation of the sodium. Rarely hyponatraemia must be treated more rapidly, i.e. the patient continues to fit. In this case where there is water overload, infusing a small volume of hypertonic saline helps shift fluid from the intracellular to the vascular space, and the extra water excreted by the kidneys. Answer 2
A. Severeiron deficiency anaemia. B. Serum ferritin. C. Iron supplementation. Advice from dietitian. Hurler’s syndrome is type IH mucopolysaccharridosis. Although normal at birth, dysmorphic features develop after the first year of life. Developmental regression is usually severe. In this patient, the developmental delay and behavioural problems meant that he ate very poorly. His dietary intake of iron was virtually nil and anaemia developed chronically. As the patient is not compromised by the anaemia, immediate blood transfusion is unnecessary, and may even be dangerous. Iron supplementation will have an effect within 2-3 days. Table
Diabetes mellitus is a possible diagnosis as it often presents with polyuria and polydipsia. On examination, the child is not necessarily dehydrated and ketotic. It is excluded in this case by measuring serum glucose. Chronic renal failure can present as polyuria (the kidneys are unable to concentrate the urine, producing urine of low osmolality) and consequent polydipsia. Features in the history may be suggestive such as recurrent urinary tract infections, but may well be absent. Diabetes insipidus (DI) is excluded as she is able to concentrate her urine during the water deprivation test. This test must be undertaken with care, as a patient with true DI can rapidly become dehydrated. Psychogenic polydipsia is common and the most likely diagnosis. It may be the symptom of emotional disturbance, in this case, the arrival of a new baby in the family. Answer 4 A. The X-rays show all the main features of rickets: l Generalized poor bone mineralization l Deformity of long bones, delayed development of epiphyses l Cupping’, ‘fraying’ and ‘splaying’ of the metaphysis (i.e. concave, irregular metaphyseal margins with a greater than normal diameter). B. The diagnosis of ‘rickets’ is confirmed by finding a high serum alkaline phosphatase, a low phosphate and a low/normal calcium. Rickets is further classified in Table 1. In the case described, results were consistent with Vitamin D deficient Rickets. Further history confirmed risk factors for Vitamin D deficiency: l l l
Prolonged breast feeding Minimal exposure to sunlight Poor dietary sources of Vitamin D.
It is important to exclude malabsorption, and screen other family members
I
Vitamin D deficiency malabsorption)
(i.e. lack of dietary
Vit D, lack of sunlight,
Vitamin
D dependent
rickets
Type I (i.e. Defect
Vitamin
D dependent
rickets
Type II (i.e. Vi1 D receptors
Vitamin D resistant hypophosphataemic
in Vit D metabolism) ‘defective’)
(hypophosphataemic) rickets (i.e. X-linked rickets, renal PO4 loss- Fanconi’s etc.)
25-HCC
I .25DHCC
PO4
PTH
Low
Low
Low
High/normal
Normal
Low
Low
Increased/normal
Normal
Normal
Low
Increased/normal
Normal
Normal
Very low
Normal
Self-assessmentquestions C. Treatment: High dose Vitamin D (1000-5000 u/d) until Alkaline Phosphatase is in normal range, then Vitamin D intake maintained at ‘normal’ level of 400U per day. Successof treatment is confirmed by biochemical parameters returning to normal. A repeat X-ray will show radiographic evidence of improvement. The risk of high dose Vitamin D is hypercalcaemia and consequent nephrocalcinosis it is important to monitor serum calcium levels during treatment.’
Answer
5
A. Long QT interval QT interval varies with heart rate. and thus the corrected QT interval (QTc) is calculated: QT interval QTc = 3~-R interval Where QT = time (sets) from beginning of Q wave to end of T wave. Normal value of QTc is < 0.45 seconds. B. Congenital long QT is associated with deafness (Jervell-Lange-Nielsen syndrome) and RomanoWard syndrome. The drug Cisapride has been associated with prolonged QT interval. C. Long term oral P-Blockers decrease the risk of arrhythmias. Effectiveness is debatable, but in infants the incidence of arrhythmia in the first year of life is decreased from 50% to less than 10%.
Answer
6
A. Main differential diagnoses l Miliary Tuberculosis l Lymphoma l Malaria. The X-ray shows typical features of Miliary TB: widespread lung infiltrates, giving a ‘snowstorm’ appearance. Other features suggesting miliary TB but not shown on this CXR are hilar lymphadenopathy and lobar infiltrates. Although the history and examination are suggestive of lymphoma, the CXR does not show the expected bilateral hilar lymphadenopathy. Neither TB nor lymphomas would show diagnostic changes on blood count. Malaria cannot be excluded on a single thick and thin film, at least three should be performed if there is a real clinical suspicion. B. Tuberculosis can be suspected with a positive mantoux/Heaf test in the absence of BCG vaccination, but may be falsely negative. Sputum and gastric aspirate cultures for mycobacteria may also be falsely negative, and a result can take up to 6 weeks. Biopsy of the liver or bone marrow with appropriate staining can often yield an early diagnosis. Similarly, the histology of biopsied lymph nodes would confirm a diagnosis of lymphoma. In this case the patient had a weakly positive mantoux, and responded dramatically to antituberculous therapy, making a biopsy unnecessary. Five weeks after therapy was commenced, Mycobacterium Tuberculosis was cultured from gastric aspirates, and full sensitivities obtained. REFERENCE3
Implantable defibrillators are effective but size limits their use to patients over 2 years old.
73
I.
Patzer L, van7 Hoff W, Dillon M. X-linked hypophosphataemic rickets: recognition. treatment prognosis. Current Paediatrics 1998; 8: 26-30.
and
Paedia/rics
0 1999 Harcourt
(I 999) 9, 70~-73
Brace & Co. Ltd
Self-assessment questions
M. Wagstaff
Question
night asking for drinks. She was passing plenty of urine, but was not enuretic. She is otherwise well and has a 2-month-old brother.
1
A lo-year-old boy presented with his first afebrile convulsion. His parents describe a 5-minute generalized tonic clonic convulsion, from which he fully recovered 90 minutes later. He is developmentally normal, with no previous medical history of note. He has become upset recently over his continued bedwetting, and his GP recently prescribed a ‘night-time tablet’, his parents say, to help. Since starting he has been dry by night.
Investigations
A water deprivation test showed the following Serum osmolality 292 mosmol/l Urine osmolality 930 mosmol/l
A. What is the likely cause of the fit? B. What investigations are necessary? C. What is the treatment? Question
A. What further investigations are necessary? B. What is the likely diagnosis?
2
Question
A 2-year-old boy with severe Hurlers Syndrome is seen in Outpatients. He has global developmental delay and behavioural problems. He is thought to be a little pale, and the blood results are as follows:
A. What is the diagnosis?
B. What other investigations are necessary? C. What treatment is required? 3
A 4-year-old girl presented with ‘excessivethirst’. She
was drinking 3 litres during the day and waking at
Dr Miles Wagstaff, Specialist Registrar United Hospital, Bath BAI 3NG, UK. Correspondence
and requests
in Paediatrics,
Tar olTprints
4
A 2-year-old boy is referred for a medical examination by his GP and social services,after a deformity of his right ankle was noted. The parents had no explanation to offer. He is still breast fed and there have been concerns raised previously about his mildly delayed motor development. He is one of three children who live with their parents and other families in a large isolated house. The Health Visitor, who is not allowed to visit, describes their lifestyle as ‘alternative’. On examination he is well grown, with no signs of trauma. He has swollen wrists and an obvious abnormality of his right ankle. X-rays are taken (see Figures I and 2).
Hb 3.9 g/d1 MCV 54 fl WCC 4.1 x 10^9/1 Plat 206 x 10”9/1
Question
Sodium 134 mmol/l Potassium 4. I mmol/l Calcium 2.2 mmol/I Urinalysis ~ culture negative
A. What features are shown on the X-rays and what is the diagnosis? B. How would you confirm the diagnosis? C. What is the treatment, and what is the major danger of treatment?
Royal
to M W.
70
Self-assessment auestions
Fig. 1
Question 5 A previously well, term baby suffers a cardiac arrest on the postnatal ward on day 2 of life. Resuscitation efforts are successful. Fig. 2
A. What does her ECG show? B. With what is this associated? C. What are the treatment options?
Question 6 A 3-year-old 3 month stay and has lost examination phadenopathy
girl presents with a fever 2 weeks after a with rclativcs in Africa. She is not eating weight. She has developed a cough. On she is pyrexial, has generalised lymand a palpable spleen (see Figure 3).
Blood tests show:
Hb 11.3 g/d1 WCC 12.4x IO”911 Pit 244 x 10”9/1 Malaria slide negative
A. What are the main differential diagnoses? B. How would you confirm the diagnosis?
Fig. 3
71
12
Current Paediatrics
Self-assessmentanswers
Answer 3
Answer 1
A. Serum glucose. A. Serum urea and creatinine. B. Psychogenic polydipsia.
A. Hyponatraemic fit with water overload, secondary to medication: He had been prescribed ‘Desmotabs’ (Vasopressin) 3 weeks earlier to control his enuresis. The risk is from water overload, and the information sheet stressesthe importance of avoiding excessiveevening drinking. As with any medicine, there is always a risk of overdose, intentional or accidental, although not in this case. B. Serum electrolytes - showing low sodium (Na 121 mmol/l) C. Water restriction. Stop medication. Water restriction is usually sufficient to correct hyponatraemia if the cause is water overload, especially in this case when the source of the water overload is removed (i.e. stop medication). Regular checking of the serum electrolytes confirms the normalisation of the sodium. Rarely hyponatraemia must be treated more rapidly, i.e. the patient continues to fit. In this case where there is water overload, infusing a small volume of hypertonic saline helps shift fluid from the intracellular to the vascular space, and the extra water excreted by the kidneys. Answer 2
A. Severeiron deficiency anaemia. B. Serum ferritin. C. Iron supplementation. Advice from dietitian. Hurler’s syndrome is type IH mucopolysaccharridosis. Although normal at birth, dysmorphic features develop after the first year of life. Developmental regression is usually severe. In this patient, the developmental delay and behavioural problems meant that he ate very poorly. His dietary intake of iron was virtually nil and anaemia developed chronically. As the patient is not compromised by the anaemia, immediate blood transfusion is unnecessary, and may even be dangerous. Iron supplementation will have an effect within 2-3 days. Table
Diabetes mellitus is a possible diagnosis as it often presents with polyuria and polydipsia. On examination, the child is not necessarily dehydrated and ketotic. It is excluded in this case by measuring serum glucose. Chronic renal failure can present as polyuria (the kidneys are unable to concentrate the urine, producing urine of low osmolality) and consequent polydipsia. Features in the history may be suggestive such as recurrent urinary tract infections, but may well be absent. Diabetes insipidus (DI) is excluded as she is able to concentrate her urine during the water deprivation test. This test must be undertaken with care, as a patient with true DI can rapidly become dehydrated. Psychogenic polydipsia is common and the most likely diagnosis. It may be the symptom of emotional disturbance, in this case, the arrival of a new baby in the family. Answer 4 A. The X-rays show all the main features of rickets: l Generalized poor bone mineralization l Deformity of long bones, delayed development of epiphyses l Cupping’, ‘fraying’ and ‘splaying’ of the metaphysis (i.e. concave, irregular metaphyseal margins with a greater than normal diameter). B. The diagnosis of ‘rickets’ is confirmed by finding a high serum alkaline phosphatase, a low phosphate and a low/normal calcium. Rickets is further classified in Table 1. In the case described, results were consistent with Vitamin D deficient Rickets. Further history confirmed risk factors for Vitamin D deficiency: l l l
Prolonged breast feeding Minimal exposure to sunlight Poor dietary sources of Vitamin D.
It is important to exclude malabsorption, and screen other family members
I
Vitamin D deficiency malabsorption)
(i.e. lack of dietary
Vit D, lack of sunlight,
Vitamin
D dependent
rickets
Type I (i.e. Defect
Vitamin
D dependent
rickets
Type II (i.e. Vi1 D receptors
Vitamin D resistant hypophosphataemic
in Vit D metabolism) ‘defective’)
(hypophosphataemic) rickets (i.e. X-linked rickets, renal PO4 loss- Fanconi’s etc.)
25-HCC
I .25DHCC
PO4
PTH
Low
Low
Low
High/normal
Normal
Low
Low
Increased/normal
Normal
Normal
Low
Increased/normal
Normal
Normal
Very low
Normal
Self-assessmentquestions C. Treatment: High dose Vitamin D (1000-5000 u/d) until Alkaline Phosphatase is in normal range, then Vitamin D intake maintained at ‘normal’ level of 400U per day. Successof treatment is confirmed by biochemical parameters returning to normal. A repeat X-ray will show radiographic evidence of improvement. The risk of high dose Vitamin D is hypercalcaemia and consequent nephrocalcinosis it is important to monitor serum calcium levels during treatment.’
Answer
5
A. Long QT interval QT interval varies with heart rate. and thus the corrected QT interval (QTc) is calculated: QT interval QTc = 3~-R interval Where QT = time (sets) from beginning of Q wave to end of T wave. Normal value of QTc is < 0.45 seconds. B. Congenital long QT is associated with deafness (Jervell-Lange-Nielsen syndrome) and RomanoWard syndrome. The drug Cisapride has been associated with prolonged QT interval. C. Long term oral P-Blockers decrease the risk of arrhythmias. Effectiveness is debatable, but in infants the incidence of arrhythmia in the first year of life is decreased from 50% to less than 10%.
Answer
6
A. Main differential diagnoses l Miliary Tuberculosis l Lymphoma l Malaria. The X-ray shows typical features of Miliary TB: widespread lung infiltrates, giving a ‘snowstorm’ appearance. Other features suggesting miliary TB but not shown on this CXR are hilar lymphadenopathy and lobar infiltrates. Although the history and examination are suggestive of lymphoma, the CXR does not show the expected bilateral hilar lymphadenopathy. Neither TB nor lymphomas would show diagnostic changes on blood count. Malaria cannot be excluded on a single thick and thin film, at least three should be performed if there is a real clinical suspicion. B. Tuberculosis can be suspected with a positive mantoux/Heaf test in the absence of BCG vaccination, but may be falsely negative. Sputum and gastric aspirate cultures for mycobacteria may also be falsely negative, and a result can take up to 6 weeks. Biopsy of the liver or bone marrow with appropriate staining can often yield an early diagnosis. Similarly, the histology of biopsied lymph nodes would confirm a diagnosis of lymphoma. In this case the patient had a weakly positive mantoux, and responded dramatically to antituberculous therapy, making a biopsy unnecessary. Five weeks after therapy was commenced, Mycobacterium Tuberculosis was cultured from gastric aspirates, and full sensitivities obtained. REFERENCE3
Implantable defibrillators are effective but size limits their use to patients over 2 years old.
73
I.
Patzer L, van7 Hoff W, Dillon M. X-linked hypophosphataemic rickets: recognition. treatment prognosis. Current Paediatrics 1998; 8: 26-30.
and