Introduction

Tuberculosis (TB) and malnutrition are two closely linked public health problems with a bidirectional relationship, due to the extraordinary ability of Mycobacterium tuberculosis to evade the human body's defences and take advantage of a weakened immune system, as well as its ability to reactivate from latent TB^1-4. Malnutrition contributes to susceptibility to infection and the development of diseases such as pulmonary TB^1,3.

According to a meta-analysis of 53 studies, malnutrition is common in males (52.3 %) in pulmonary TB patients and in vulnerable populations, with a prevalence of 11.7 %, which warrants the need for strict monitoring in critically ill patients^5,6.

Anti-tuberculosis treatment is divided into two phases: an intensive phase of 8 weeks, in which drugs such as isoniazid, rifampicin, pyrazinamide and ethambutol are used, and a 16-week continuation phase that includes isoniazid and rifampicin⁷.

The City of El Alto, located at an altitude of 4150 metres above sea level (masl) in the La Paz department of the Plurinational State of Bolivia⁸. As in Tibet, 53 % of Tibetans live at high altitudes above 3500 metres above sea level⁹. These populations have a remarkable physiological adaptation to life in hypoxic conditions, and have unique conditions for studying this interaction at high altitude. Studies have shown that Tibetan adolescents and adults have significantly higher forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) than individuals born and living at high altitude, indicating a pattern of adaptation to hypoxia at high altitude¹⁰.

Under these conditions, it is important to note that the normal arterial partial pressure of oxygen (PaO2) in the cities of La Paz and El Alto (3100 to 4150 masl) is 60 mmHg, one third less than at sea level⁸. This may exacerbate hypoxaemia caused by pulmonary TB, including alveolar hypoventilation, impaired diffusion or ventilation-perfusion imbalance. However, to our knowledge, scientific evidence in this geographical context is limited on the interaction between pulmonary TB and severe malnutrition.

This case report aims to highlight the therapeutic challenges and strategies needed to address these complexities in an extreme altitude setting.

Case presentation

A 19-year-old male patient, resident in the City of El Alto, Plurinational State of Bolivia, located at 4150 m above sea level. He presented with a clinical picture of 4 months of evolution, characterised by abdominal pain, dyspnoea, progressive weight loss, nocturnal diaphoresis, oedema of the lower limbs and anaemia. Further anamnesis revealed that his mother was diagnosed with pulmonary TB and started anti-tuberculosis treatment. The patient had no known chronic medical illnesses or surgeries.

On physical examination, blood pressure was 93/60 mmHg, pulse 92 beats per minute, axillary temperature 36.5° C, respiratory rate 16 breaths per minute and oxygen saturation 95 % with supplemental oxygen of 2 L min^-1. Body mass index was 12.1 kg m^-2. Chest examination showed marked bony prominences of rachitic thorax type, and pulmonary auscultation showed crackles in the right and left suprascapular regions. Abdominal examination revealed an excavated abdomen, painful on deep palpation in the epigastric, mesogastric and right iliac fossa regions. He had pale oral mucosa, tongue and conjunctivae, dehydrated skin, also evident on the trunk and extremities (Figure 1-2).

Figura 1 Desnutrición severa en decúbito sentado con vista anterior 

Figura 2 Desnutrición severa en posición de sentado con vista lateral 

Following laboratory tests (Table 1), the complete blood count revealed severe anaemia, leukopenia and thrombocytopenia. Liver enzymes aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase and C-reactive protein were elevated. Serum albumin and serum potassium were decreased. Serial sputum smear microscopy was positive with 3 crosses. HIV test was non-reactive. Chest X-ray revealed radiopaque infiltrates in the bilateral infraclavicular region with left predominance (Figure 3). Chest CT scan showed alveolar infiltrates and microcavitations in the upper lobes (Figure 4).

Figura 3 Radiografía posteroanterior (PA) de tórax 

The initial impression was active pulmonary TB with high bacillary burden and severe malnutrition. Intensive phase anti-TB treatment was started with 4 tablets of HRZE orally in a single dose (single dose), including isoniazid (H) 225 mg, rifampicin (R) 450 mg, pyrazinamide (Z) 1000 mg and ethambutol (E) 600 mg, administered from Monday to Saturday. Accompanied by nutritional support with hyperproteic and hypercaloric food. He also received blood transfusion of 2 units of whole blood. Intranasal oxygen was administered at 2 L min^-1. Two months after starting anti-tuberculosis treatment, the patient presented complete clinical recovery, negative sputum smear test and resolution of alveolar infiltrates in the chest CT scan.

Figura 4 Tomografía axial computarizada (TAC) de tórax con proyección coronal 

Discussion

The interaction of pulmonary TB is closely related to severe malnutrition¹¹ and is further complicated by living conditions at high altitudes such as the Tibetan Plateau (≥3000 m asl), with the proportion of TB (50 %) and high nutritional risk, as noted in a cross-sectional observational study with a total of 289 Tibetan patients hospitalized in the Department of Respiratory and Critical Care Medicine of the People's Hospital of the Tibet Autonomous Region in Lhasa¹². While severe malnutrition, living at high altitude and the development of TB pose significant challenges, they also offer opportunities for intervention, as was the case in our case.

In a meta-analysis of 53 studies with pulmonary TB, the prevalence of malnutrition was (48 %)⁵. In a small cross-sectional study involving 54 newly laboratory diagnosed TB patients seen at a tertiary care hospital in Gangtok, Sikkim, India, a Himalayan part situated at a mean altitude of 5412 ft above sea level (1650 m), it was found that as vitamin D levels decrease in the patient, the risk of developing TB was higher with Odds ratio = 3.2 (p = 0.001)¹³ and corroborated with a meta-analysis of 69 studies, vitamin D deficiency was identified as a risk factor for TB (OR = 2.19, 95 % CI, 1.76-2.73, p = <0.001)¹⁴. Although vitamin D levels were not determined in our case, to correlate TB and vitamin D deficiency, it is reasonable to hypothesize that TB patients have lower serum levels of vitamin D than healthy individuals and would contribute to the development of TB in high altitude situations, due to the clothing pattern of its inhabitants, as well as exposure to sunlight.

The interaction of these 2 factors (TB and malnutrition) requires a comprehensive approach to management in high altitude geographic areas. Malnutrition is a cause of secondary immunodeficiency and a key comorbidity in TB cases¹⁵. While malnutrition and TB pose significant challenges for management, they also offer opportunities for intervention, as was the case in our case.

Our results also point to several blood biomarkers, including total protein, albumin, hemoglobin, and C-reactive protein (CRP). As expected, the level of total protein and serum albumin were low, while serum CRP levels were increased by the same tuberculosis disease, as pointed out in the meta-analysis study of 111 studies and highlighted that they are useful biochemical indicators of malnutrition, even with the presence of chronic inflammation¹⁶.

A study conducted at the Guanzhou Chest Hospital with 952 hospitalized patients, showed that nutritional status is significantly associated with the severity of pulmonary TB, and the average immune function, the effects of nutritional status on the severity of pulmonary TB and maintaining optimal immune function, help reduce the risk of severe pulmonary TB¹⁷. At the same time, it is expected that nutritional status (prognostic nutritional index) and immune status, with the reduction of platelet-lymphocyte ratio levels, become early diagnostic markers of TB severity¹⁸, as observed in the laboratory findings of our case.

Conclusion

This clinical case, originated in the Hospital del Norte of El Alto, Plurinational State of Bolivia, highlights the interaction between pulmonary TB, severe malnutrition and the unique conditions of high altitude, as evidenced in a young resident of El Alto, La Paz-Plurinational State of Bolivia. Chronic hypoxia associated with altitude not only exacerbates the effects of malnutrition and TB, but also poses unique challenges for clinical management. The implementation of a multidisciplinary approach, including intensive anti-TB treatment, nutritional support and oxygen therapy, allowed the patient to achieve full recovery.

The experience gained from this case can contribute as a reference to improve treatment strategies in similar vulnerable populations. Early diagnosis and timely management are crucial to reduce the high burden of TB in countries with adverse environmental and geographic conditions.

This report emphasizes the importance of recognizing and treating the bidirectional interactions between infectious disease, nutritional status and adverse environmental conditions. Furthermore, it highlights the need to develop specific management strategies for populations at extreme altitudes, as well as to conduct additional research exploring the pathophysiological mechanisms and most effective therapeutic interventions in these contexts.