Post-mortem computed tomography in the investigation of conflict and terrorist related deaths: UK military experience of developing a multidisciplinary service.

This paper discusses the introduction, development and utility of post-mortem imaging relating specifically to conflict-related and terrorist-related deaths and considers the use of computed tomography (CT) in the investigations. We demonstrate how a multi-disciplinary approach involving direct communication between forensic pathologist and radiologist can maximise evidential yield, reduce the need for unnecessary dissection and further our understanding of such injuries. This summarises our shared experience of hundreds of cases, each having been individually discussed and reviewed, and has helped shape our understanding of conflict injury as well as contributing to the development of mitigation strategies and adaptations to protective equipment. A series of clinical cases are presented to demonstrate some of the strengths and weaknesses of the process.

Focused Assessment with Sonography in Trauma (FAST) performance in paediatric conflict injury.

AIM: To evaluate the efficacy of Focused Assessment with Sonography in Trauma (FAST) in a paediatric population with a substantial proportion of penetrating abdominal injuries. MATERIALS AND METHODS: FAST and computed tomography (CT) abdomen findings were compared for 98 children who presented to Camp Bastion during the war in Afghanistan in 2011. FAST performance was compared to the reference standard of free fluid detected on CT. Whether children presented alone or as part of a group was also ascertained from the radiology database. RESULTS: Of the 98 patients, 20 had free fluid on CT and 15 were FAST positive. Fourteen of the 98 (14%) had penetrating wounds to the abdominal cavity. For the whole cohort FAST sensitivity was 65% (41-85%) and specificity 97% (91-100%). For those with penetrating abdominal injury sensitivity was 64% (31-89%) and specificity was 100% (40-100%). In total, 45% arrived at the same time as another casualty, and 30% arrived with other injured children. CONCLUSION: FAST performance in this population was similar to that reported in the context of paediatric blunt trauma, with high specificity for intra-abdominal free fluid. This is the first time this has been demonstrated in a cohort containing children with penetrating abdominal trauma. A substantial proportion of children presented as part of a group, necessitating simultaneous triage of multiple injured patients. FAST has a role to play in conflict medicine and mass casualty scenarios where rapid access to CT may not be feasible.

Environment at the time of injury determines injury patterns in pelvic blast.

The use of explosives by terrorists, or during armed conflict, remains a major global threat. Increasingly, these events occur in the civilian domain, and can potentially lead to injury and loss of life, on a very large scale. The environment at the time of detonation is known to result in different injury patterns in casualties exposed to blast, which is highly relevant to injury mitigation analyses. We describe differences in pelvic injury patterns in relation to different environments, from casualties that presented to the deployed UK military hospitals in Iraq and Afghanistan. A casualty on foot when injured typically sustains an unstable pelvic fracture pattern, which is commonly the cause of death. These casualties die from blood loss, meaning treatment in these should focus on early pelvic haemorrhage control. In contrast, casualties injured in vehicle present a different pattern, possibly caused by direct loading via the seat, which does not result in pelvic instability. Fatalities in this cohort are from injuries to other body regions, in particular the head and the torso and who may require urgent neurosurgery or thoracotomy as life-saving interventions. A different strategy is therefore required for mounted and dismounted casualties in order to increase survivors.

Deployed military general internal physician's toolkit: the recent past and near future.

INTRODUCTION: The role of the military physician in Deployed Hospital Care involves the diagnosis and management of a wide variety of disease states. Broad clinical skills need to be complemented by judicious use of a limited array of investigations. No study has specifically quantified what investigations physicians use on operations. METHODS: A retrospective cross-sectional study was performed to ascertain what investigations were undertaken on all patients managed by the General Internal Medicine teams over a 14 month period during a recent enduring operation in Afghanistan. A record was also made of investigations that were unavailable but considered desirable by the treating physician in order to inform clinical or occupational decisions. RESULTS: 676 patients were admitted during the study period. Blood tests were performed in 96% of patients, plain radiographs in 50%, CT in 12% and ultrasound in 12%. An ECG was performed in over half (57%) and a peak flow in 11%. The most desirable, but unavailable, investigations were cardiac monitoring and echocardiography (24% and 12% of patients, respectively). DISCUSSION: The data produced by this study both identified and quantified the investigations used by physicians during a mature operational deployment. This can be used in addition to accurate medical intelligence to inform and rationalise the diagnostic requirements for future operations as well as the provision of training. Technological advancements, particularly in weight and portability, are likely to enable more complex investigational modalities to be performed further forward on military deployments.

Does preliminary optimisation of an anatomically correct skull-brain model using simple simulants produce clinically realistic ballistic injury fracture patterns?

Ballistic head injury remains a significant threat to military personnel. Studying such injuries requires a model that can be used with a military helmet. This paper describes further work on a skull-brain model using skulls made from three different polyurethane plastics and a series of skull 'fills' to simulate brain (3, 5, 7 and 10% gelatine by mass and PermaGel™). The models were subjected to ballistic impact from 7.62 × 39 mm mild steel core bullets. The first part of the work compares the different polyurethanes (mean bullet muzzle velocity of 708 m/s), and the second part compares the different fills (mean bullet muzzle velocity of 680 m/s). The impact events were filmed using high speed cameras. The resulting fracture patterns in the skulls were reviewed and scored by five clinicians experienced in assessing penetrating head injury. In over half of the models, one or more assessors felt aspects of the fracture pattern were close to real injury. Limitations of the model include the skull being manufactured in two parts and the lack of a realistic skin layer. Further work is ongoing to address these.

Primary blast lung injury - a review.

Bomb or explosion-blast injuries are likely to be increasingly encountered as terrorist activity increases and pre-hospital medical care improves. We therefore reviewed the epidemiology, pathophysiology and treatment of primary blast lung injury. In addition to contemporary military publications and expert recommendation, an EMBASE and MEDLINE search of English speaking journals was undertaken using the medical subject headings (MeSHs) 'blast injury' and 'lung injury'. Review articles, retrospective case series, and controlled animal modelling studies published since 2000 were evaluated. 6-11% of military casualties in recent conflicts have suffered primary blast lung injury but the incidence increases to more than 90% in terrorist attacks occurring in enclosed spaces such as trains. The majority of victims require mechanical ventilation and intensive care management. Specific therapies do not exist and treatment is supportive utilizing current best practice. Understanding the consequences and supportive therapies available to treat primary blast lung injury are important for anaesthetists.

Case suitability for definitive through knee amputation following lower extremity blast trauma: analysis of 146 combat casualties, 2008-2010.

INTRODUCTION: Analysis of recent UK Armed Forces combat casualty data has highlighted a significant number of through joint traumatic amputations (TAs), most commonly through knee (through knee amputations (TKAs)). Previously, a consensus statement on lower limb amputation from the UK Defence Medical Services reported better outcomes in some patients with TKAs when compared with those with above knee amputations. This study sought to define the proportion of recent combat casualties sustaining severe lower extremity trauma with acute osseous and soft tissue injury anatomy amenable to definitive TKA. METHODS: The UK Joint Theatre Trauma Registry and post mortem CT (PM-CT) databases were used to identify all UK Armed Forces personnel (survivors and fatalities) sustaining a major extremity TA (through/proximal to wrist or ankle joint) between August 2008 and August 2010. Through knee and all below knee TAs were grouped as 'potential TKAs' (pTKAs), that is, possible candidates for definitive TKA. RESULTS: 146 Cases (75 survivors and 71 fatalities) sustaining 271 TAs (130 in survivors, 141 in fatalities) were identified. The through-joint TA rate was 47/271 (17.3%); 34/47 through-joint injuries (72.3%) were TKAs. Overall, 63/130 TAs in survivors and 66/140 TAs in fatalities merited analysis as the pTKA group. Detailed anatomical data on pre-debridement osseous and soft tissue injury levels were only consistently available for fatalities through PM-CT findings. Further analysis of the soft tissue injury profile revealed that a definitive TKA in the pTKA group (all BKAs as well as TKAs) would have been proximal to the zone of injury (ZOI) in only 3/66 cases. CONCLUSIONS: Traumatic TKAs following explosive blast are more common than previously reported. The majority of lower limb TAs are skeletally amenable to a definitive TKA. Maximising residual stump length carries the risks of definitive level amputation within the original ZOI but this study demonstrates that the proximal extent of the soft tissue injury may frequently make this unavoidable. Further work is required to determine the relative merits of definitive below, through and above knee amputations in the short, medium and long term to ensure survivors are subject to minimal complications while maintaining capacity to achieve optimal functional outcomes.

Blast-mediated traumatic amputation: evidence for a revised, multiple injury mechanism theory.

INTRODUCTION: The accepted mechanism of blast-mediated traumatic amputation (TA) is blast wave induced fracture followed by limb avulsion from the blast wind, generating a transosseous amputation. Blast-mediated through-joint TAs were considered extremely rare with published prevalence <2%. Previous studies have also suggested that TA is frequently associated with fatal primary blast lung injury (PBLI). However, recent evidence suggests that the mechanism of TA and the link with fatal primary blast exposure merit review. METHODS: A trauma registry (UK Joint Theatre Trauma Registry) and postmortem CT (PM-CT) database were used to identify casualties (survivors and deaths) sustaining a blast-mediated TA in the 2 years from August 2008. TA metrics and associated significant injuries were recorded. Detailed anatomical data on extremity predebridement osseous and soft tissue injuries were only consistently available for deaths through comprehensive PM-CT imaging. RESULTS: 146 cases (75 survivors and 71 deaths) sustaining 271 TAs (130 in survivors and 141 in deaths) were identified. The lower limb was most commonly affected (117/130 in survivors, 123/141 in deaths). The overall through-joint TA rate was 47/271 (17.3%) and 34/47 through-joint injuries (72.3%) were through knee. More detailed anatomical analysis facilitated by PM-CT imaging revealed only 9/34 through-joint TAs had a contiguous fracture (ie, intra-articular involving the joint through which TA occurred), 18/34 had no fracture and 7/34 had a non-contiguous (ie, remote from the level of TA) fracture. No relationship between PBLI and TA was evident. CONCLUSIONS: The previously reported link between TA and PBLI was not present, calling into question the significance of primary blast injury in causation of blast mediated TAs. Furthermore, the accepted mechanism of injury can't account for the significant number of through-joint TAs. The high rate of through-joint TAs with either no associated fracture or a non-contiguous fracture (74%) is supportive of pure flail as a mechanism for blast-mediated TA.

Understanding the burden of injury in children from conflict: an analysis of radiological imaging from a Role 3 hospital in Afghanistan in 2011.

INTRODUCTION: There is a need for quality medical care for children injured in conflict, but a description of injuries and injury burden from blast and ballistic mechanisms is lacking. The radiology records of children imaged during the war in Afghanistan represent a valuable source of information about the patterns of paediatric conflict injuries. METHODS: The UK military radiological database was searched for all paediatric presentations to Camp Bastion during 2011. Reports and original images were reviewed to determine location and severity of injuries sustained. Additional information was obtained from imaging request forms and the Joint Theatre Trauma Register, a database of those treated at UK medical facilities in Iraq and Afghanistan. RESULTS: Radiology was available for 219 children. 71% underwent CT scanning. 46% suffered blast injury, 22% gunshot wounds (GSWs), and 32% disease and non-battle injuries (DNBIs). 3% had penetrating head injury, 11% penetrating abdominal trauma and 8% lower limb amputation, rates far exceeding those found in civilian practice. Compared with those with DNBI, those with blast or GSW were more likely to have serious (Abbreviated Injury Score, AIS, ≥3) injuries (median no. AIS ≥3 injuries were 1 for blast, 1 for GSW and 0 for DNBI, p<0.05) and children exposed to blast were more likely to have multiple body regions with serious injuries (OR for multiple AIS ≥3 injuries for blast vs DNBI=5.811 CI [1.877 to 17.993], p<0.05). CONCLUSIONS: Paediatric conflict injuries are severe, and clinicians used only to civilian practice may be unprepared for the nature and severity of injuries inflicted on children in conflict. Whole-body CT for those with conflict-related injuries, especially blast, is hugely valuable. We recommend that CT is used for paediatric assessment in blast and ballistic incidents and that national imaging guidelines amend the threshold for doing so.

Using CT scans to determine the optimal sizes of hard armour plates to protect the torso for UK female Armed Forces personnel.

INTRODUCTION: Hard armour plates provide coverage to essential anatomical structures in the torso that, if injured, would likely be responsible for death before damage control surgery can be undertaken. Existing front and rear OSPREY plates in conjunction with Mark 2 plates used at the sides in current UK Armed Forces personal armour systems are provided in a single size, used by both female and male users. METHODS: CT scans of 45 female UK military personnel were analysed. Distances between anatomical structures representing threshold (absolute minimum) and objective (the maximum level of coverage beyond which there is limited further benefit) coverage of the torso were determined and compared with OSPREY and Mark 2 plate dimensions. Sample characteristics were compared with the 2006/2007 UK Armed Forces Anthropometric Survey. RESULTS: No statistical difference was found between sample means for stature (p=0.131) and mass (p=0.853) from those of the anthropometric survey in this sample. The height of both the front OSPREY plates exceeded the threshold coverage (suprasternal notch to lower border of the 10th rib) for all women studied. The height of the Mark 2 plate exceeds the objective coverage from the side for all women studied. CONCLUSIONS: Based on a plate height providing threshold coverage of all women up to the 50th percentile, the height of the front and rear OSPREY plates could be reduced by 36mm and 31mm respectively. Based on a presumption that a side plate should cover up to the 95th percentile, the Mark 2 plate achieves the objective height and width for the female population studied. Strong evidence was found to support the UK Ministry of Defence requirement for procurement of new front and rear plates of multiple heights for both female and male users.

Spinal fractures in current military deployments.

OBJECTIVE: To describe spinal fracture patterns presenting to deployed medical facilities during recent military operations. METHODS: Retrospective analysis of the United Kingdom Centre for Defence Imaging Computed Tomography database, 2005-2009. Fractures are classified, mechanism noted and associated injuries recorded. Statistical analysis is by Fisher's Exact test. RESULTS: 128 fractures in 57 casualties are analysed. Ballistic (79%) and non-ballistic mechanisms contribute to vertebral fracture at all regions of the spinal column in patients treated at deployed medical facilities. There is a high incidence of lumbar spine fractures, which are more likely to be due to explosion than gunshot wounding (p < 0.05). Two thirds of thoracolumbar spine fractures caused by explosive devices are unstable and are mainly burst-fractures in configuration. 60% of spinal fracture patients had concomitant injuries. There is a strong relationship between spinal fractures caused by explosions and lower limb fractures. CONCLUSION: Injuries to the spine caused by explosive devices account for greater numbers, greater associated morbidity and increasing complexity than other means of spinal injury managed in contemporary warfare. With the predominance of explosive injury in current conflict, this work provides the first detail of an evolving injury mechanism with implications for injury mitigation research.

A retrospective audit of the timescales involved in the diagnosis and management of suspected Achilles tendon ruptures at a single National Health Service trust: A quality service improvement and redesign project.

Introduction: The Achilles tendon is the most frequently ruptured tendon. Prompt diagnosis of this injury ensures optimal management decisions are instituted early ensuring the best outcome and patient experience, at minimal cost to the United Kingdom National Health Service. Despite this, regional and national variations to diagnosis and management exist, with anecdotal evidence of inefficiencies in the local patient pathway. To explore this further, a retrospective departmental audit of timescales from presentation to ultrasound diagnosis and definitive treatment decision was undertaken. Methods: All suspected Achilles tendon ruptures in 2018 were identified through electronic and written patient records, and information on timescales involved in the diagnosis and management of each compiled. Descriptive statistics were used to map each step of the pathway and timescales involved, with performance assessed against local departmental standards and the Swansea Morriston Achilles Rupture Treatment (SMART) protocol. Results: In total, 119 patients were identified, of which 113 received an ultrasound examination. Local departmental standards were met in the majority of cases, with 78% (n = 88) diagnosed by ultrasound within one week of the request and 83% (n = 91) given a treatment decision within two weeks of presentation. However, this was suboptimal when compared with timeframes utilised for developing the SMART protocol, with only 7% (n = 8) scanned within 48 hours of presentation. Conclusions: Key areas of the patient pathway were identified for quality service improvement and redesign, with multidisciplinary discussion resulting in the development of a revised patient pathway which expedites diagnosis and treatment for these injuries.

Electronic tags reveal behaviour of captured and discarded fish.

Internally implanted data storage tags (DST) recording hydrostatic pressure (depth) and temperature in Atlantic cod Gadus morhua were used to track the behaviour of nine individuals during fishing operations. Gadus morhua showed identifiable and characteristic behavioural responses to different capture processes. In a unique observation, one fish survived being discarded and upon return to the seabed exhibited a cessation of activity comparable to observations on stressed fish under laboratory conditions.

Effect of insulin on systemic and renal handling of albumin in nondiabetic and NIDDM subjects.

Insulin resistance and hyperinsulinemia cluster with microalbuminuria in both diabetic and nondiabetic subjects, but the mechanism underlying this association is unknown. To test the hypothesis that insulin influences protein permeability, we measured the albumin transcapillary escape rate (TER) by the (131)I-labeled albumin technique in 12 healthy volunteers and 12 normoalbuminuric NIDDM patients (fasting plasma glucose, 10.9 +/- 1.3 mmol/l) during 4 h of isoglycemia with high (1.1 mU x min(-1) x kg(-1)) or, on a different day, low (0.1 mU x min(-1) x kg(-1)) insulin infusion. In both patients and control subjects, high insulin was associated with a 7% decrease in blood volume (P = 0.006) and a 6% decrease in diastolic blood pressure (P < 0.02), these two changes being related to one another (r = 0.56, P < 0.01). Basal albumin TER was similar in patients (8.4 +/- 0.5% x h(-1)) and control subjects (7.7 +/- 0.7% x h(-1)) and was not significantly changed by high insulin in either group (patients vs. control subjects, 7.3 +/- 0.9 vs. 6.2 +/- 0.4% x h(-1); NS vs. low insulin). In contrast, high insulin increased renal albumin excretion (from 3.6 +/- 0.8 to 5.4 +/- 1.1 microg/min, P < 0.01) and clearance rate (0.09 +/- 0.02 to 0.13 +/- 0.03 microl/min, P < 0.001) in patients but not in control subjects. To localize the effect of insulin along the nephron, we measured the urinary excretion of N-acetyl-beta-D-glucosaminidase (beta-NAG), released by the proximal tubule; retinol-binding protein (RBP), reabsorbed by the proximal tubule; and Tamm-Horsfall protein (THP) and epidermal growth factor (EGF), both secreted by the distal tubule. For both beta-NAG and RBP, but not EGF or THP, insulin enhanced urinary excretion (diabetics vs. controls: beta-NAG, 0.48 vs. -0.15 microU/min [P = 0.03]; RBP, 78 vs. -32 ng/min [P = 0.05]). In conclusion, physiological hyperinsulinemia does not affect systemic albumin permeability in healthy subjects or normoalbuminuric NIDDM patients. In contrast, in NIDDM patients, but not in healthy subjects, insulin increases the urinary excretion of albumin and protein markers of proximal tubular function. The significance of this finding for the pathogenesis of diabetic nephropathy remains to be established.

Radiology.

The speciality of Radiology is little over 100 years old yet the expansion and diversity within the speciality is accelerating. This paper reviews the recent technological developments by modality, their impact on medical imaging and touches on some research techniques which may find their way into mainstream imaging.

The role of computerised tomography in predicting visual outcome in ocular trauma patients.

PURPOSE: Ocular blast injuries in the military setting are particularly associated with significant maxillofacial trauma and/or brain injury. The opportunity to perform a comprehensive ophthalmic evaluation is frequently limited in the acute multiple trauma scenario. We aim to describe the relationship between the clinical effects of acute ocular and orbital blast trauma with the findings on computerised tomography (CT). METHODS: This was a retrospective consecutive case series of all soldiers with facial and/or suspected ocular injuries. A total of 80 eyes that had suffered blast injuries of varying severity were studied. Assessment of orbital and ocular CT images were performed by military consultant radiologists. A comparison was made with actual clinical findings. Statistical analysis was performed using Fisher's exact test. RESULTS: No pathological findings were described in 37 of the 80 eyes imaged by orbital and ocular CT scans. Clinically, these eyes and orbits were all found to be intact, or had minor trauma. All foreign bodies and penetrating eye injuries were successfully diagnosed by CT. Absence of an orbital fracture did not rule out a globe injury. However, a corneal or scleral defect was less likely when an orbital fracture was absent. CONCLUSION: The eye is a delicate structure prone to injury that requires urgent repair if breached. It is difficult to assess thoroughly in the unconscious or distressed patient. In this context, CT imaging is invaluable to be able to make a relatively confident prediction of clinical findings and decide upon the necessity for acute ophthalmic surgical intervention.

Comparison of a medium supplement--'Nu-Serum'--and foetal calf serum in RPMI 1640 used for the murine allogeneic mixed lymphocyte reaction.

A commercially available medium supplement, Nu-Serum, was compared with foetal calf serum for its ability to support the murine allogeneic mixed lymphocyte reaction. Nu-Serum supported proliferation whilst at the same time producing significantly lower counts in unstimulated cultures. There was considerably less batch-to-batch variation with Nu-Serum than with foetal calf serum, which obviated the need for pretesting in order to find a suitable batch.

Immunosuppressive proteins secreted by the gastrointestinal nematode parasite Heligmosomoides polygyrus.

Experiments are described in which the conditions for the production, assay and isolation of immunomodulatory factors from the excretory-secretory (ES) products of Heligmosomoides polygyrus have been standardized. For the inhibition of an in vitro antibody response to keyhole limpet haemocyanin, immunosuppressive activity was most reproducibly produced by 10-20-day-old adult worms maintained in culture for 24 h. This activity was relatively stable at room temperature, at 50 degrees C and pH 2, but was destroyed by boiling. Immunosuppressive activity was eluted from Sephadex G-100 in fractions preceding those containing the bulk of ES proteins, and resolved on sodium dodecyl sulphate-polyacrylamide gel electrophoresis with molecular masses of 67, 54 and 20 kDa. The relative purity of these factors was confirmed by iso-electric focusing, where immunosuppressive activity was associated with proteins of pI values of approximately 4.2 and 4.35.

Evaluation and assessment of new disposable strip for determination of plasma potassium concentration.

Overall laboratory reproducibility for the Ames Seralyzer and plasma potassium test strips was less than 4% within the plasma reference range; and linearity extended from 2.1 to 10.2 mmol/l. Neither bilirubin nor lipaemia interfered in the analysis and selectivity for potassium over sodium was 450:1. Laboratory comparison with automated flame photometry and an indirect ion selective electrode showed a Seralyzer bias of +0.10 (+/- 25D 0.26) and +0.11 (0.27) mmol/l. Against flame photometry, comparison of analyses by six doctors from a coronary care unit and four nurses from a renal dialysis unit showed smaller positive biases (0.06 and 0.02 mmol/l) but substantially larger error ranges (0.43 and 0.55 mmol/l, respectively). Some 49% of the nurses' and 37% of the doctors' results differed from laboratory values by more than 0.2 mmol/l. Potassium test strip results proved acceptably comparable and reproducible when produced by an experienced analyst, but greater variability in clinical hands rendered the system unsuitable for precise monitoring of potassium concentration.

Assessment of chemotherapy-associated nephrotoxicity in children with cancer.

Assessment of the toxicity caused by chemotherapy in children with cancer has become more important as the number of long-term survivors has continued to increase. It is vital to monitor both acute life-threatening adverse effects and long-term toxicity that may impair the child's development and cause permanent morbidity. Renal damage may follow treatment with cytotoxic drugs, especially cisplatin or ifosfamide, and lead to glomerular, proximal tubular or distal tubular impairment or to any combination of these. Greater understanding of nephrotoxicity and of its prevention may enable the use of more intensive schedules or of higher doses of potentially nephrotoxic chemotherapy. However, the evaluation of cytotoxic drug-induced nephrotoxicity has frequently depended mainly on measurement of the plasma creatinine concentration, which may remain normal despite substantial glomerular impairment or severe tubular dysfunction. Detailed assessment of nephrotoxicity depends on an understanding of normal renal physiology and requires evaluation of all aspects of function. A comprehensive but simple investigatory protocol that enables assessment of the nature and severity of nephrotoxicity in children is described, which can be performed without admission to hospital. Glomerular function is assessed by measurement of the glomerular filtration rate from the plasma clearance of [51Cr]-ethylenediaminetetraacetic acid ([51Cr]-EDTA). Proximal nephron function is evaluated in three ways: by measurement of the concentration of calcium, magnesium, phosphate, glucose and urate in blood and urine along with calculations of their fractional excretion and of the renal threshold for phosphate; by determination of the excretion in urine of low-molecular-weight proteins (e.g. retinol-binding protein); and by investigation of urinary bicarbonate excretion in patients who are acidotic. Distal nephron function is initially investigated by examination of the concentration (osmolality) and acidification (pH) of an early morning sample of urine. Finally, a group of general investigations is performed, including quantitation of urinary excretion of renal tubular enzymes (e.g. N-acetylglucosaminidase) and measurement of blood pressure.